diff --git a/.changeset/shaggy-pumas-rush.md b/.changeset/shaggy-pumas-rush.md
new file mode 100644
index 0000000000..0be76c3e58
--- /dev/null
+++ b/.changeset/shaggy-pumas-rush.md
@@ -0,0 +1,6 @@
+---
+"gitbook-v2": patch
+"gitbook": patch
+---
+
+Introduce the concept of slim documents
diff --git a/packages/gitbook-v2/src/lib/data/api.ts b/packages/gitbook-v2/src/lib/data/api.ts
index 20e495656e..137ff158be 100644
--- a/packages/gitbook-v2/src/lib/data/api.ts
+++ b/packages/gitbook-v2/src/lib/data/api.ts
@@ -1,3 +1,4 @@
+import { getSlimJSONDocument } from '@/lib/slim-document';
 import { trace } from '@/lib/tracing';
 import {
     type ComputedContentSource,
@@ -779,7 +780,7 @@ const getDocumentUncached = async (
                 cacheTag(...getCacheTagsFromResponse(res));
                 cacheLife('max');
             }
-            return res.data;
+            return getSlimJSONDocument(res.data);
         });
     });
 };
@@ -872,7 +873,7 @@ const getComputedDocumentUncached = async (
                     cacheTag(...getCacheTagsFromResponse(res));
                     cacheLife('max');
                 }
-                return res.data;
+                return getSlimJSONDocument(res.data);
             });
         }
     );
diff --git a/packages/gitbook-v2/src/lib/data/pages.ts b/packages/gitbook-v2/src/lib/data/pages.ts
index 4324254d9b..388fcff7c7 100644
--- a/packages/gitbook-v2/src/lib/data/pages.ts
+++ b/packages/gitbook-v2/src/lib/data/pages.ts
@@ -1,4 +1,5 @@
-import type { JSONDocument, RevisionPageDocument, Space } from '@gitbook/api';
+import type { SlimJSONDocument } from '@/lib/slim-document';
+import type { RevisionPageDocument, Space } from '@gitbook/api';
 import { getDataOrNull } from './errors';
 import type { GitBookDataFetcher } from './types';
 
@@ -9,7 +10,7 @@ export async function getPageDocument(
     dataFetcher: GitBookDataFetcher,
     space: Space,
     page: RevisionPageDocument
-): Promise<JSONDocument | null> {
+): Promise<SlimJSONDocument | null> {
     if (page.documentId) {
         return getDataOrNull(
             dataFetcher.getDocument({ spaceId: space.id, documentId: page.documentId })
diff --git a/packages/gitbook-v2/src/lib/data/types.ts b/packages/gitbook-v2/src/lib/data/types.ts
index 178a0ba77d..ba8f3eca5f 100644
--- a/packages/gitbook-v2/src/lib/data/types.ts
+++ b/packages/gitbook-v2/src/lib/data/types.ts
@@ -1,3 +1,4 @@
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import type * as api from '@gitbook/api';
 
 export type DataFetcherErrorData = {
@@ -110,7 +111,7 @@ export interface GitBookDataFetcher {
      * Get a document by its space ID and document ID.
      */
     getDocument(params: { spaceId: string; documentId: string }): Promise<
-        DataFetcherResponse<api.JSONDocument>
+        DataFetcherResponse<SlimJSONDocument>
     >;
 
     /**
@@ -121,7 +122,7 @@ export interface GitBookDataFetcher {
         spaceId: string;
         source: api.ComputedContentSource;
         seed: string;
-    }): Promise<DataFetcherResponse<api.JSONDocument>>;
+    }): Promise<DataFetcherResponse<SlimJSONDocument>>;
 
     /**
      * Get a reusable content by its space ID, revision ID and reusable content ID.
diff --git a/packages/gitbook/src/components/DocumentView/Block.tsx b/packages/gitbook/src/components/DocumentView/Block.tsx
index f3acafce0d..c842a45916 100644
--- a/packages/gitbook/src/components/DocumentView/Block.tsx
+++ b/packages/gitbook/src/components/DocumentView/Block.tsx
@@ -1,4 +1,3 @@
-import type { DocumentBlock, JSONDocument } from '@gitbook/api';
 import React from 'react';
 
 import {
@@ -10,6 +9,7 @@ import {
 } from '@/components/primitives';
 import type { ClassValue } from '@/lib/tailwind';
 
+import type { SlimDocumentBlock, SlimJSONDocument } from '@/lib/slim-document';
 import { BlockContentRef } from './BlockContentRef';
 import { CodeBlock } from './CodeBlock';
 import { Divider } from './Divider';
@@ -34,10 +34,10 @@ import { StepperStep } from './StepperStep';
 import { Table } from './Table';
 import { Tabs } from './Tabs';
 
-export interface BlockProps<Block extends DocumentBlock> extends DocumentContextProps {
+export interface BlockProps<Block extends SlimDocumentBlock> extends DocumentContextProps {
     block: Block;
-    document: JSONDocument;
-    ancestorBlocks: DocumentBlock[];
+    document: SlimJSONDocument;
+    ancestorBlocks: SlimDocumentBlock[];
     /** If true, we estimate that the block will be outside the initial viewport */
     isEstimatedOffscreen: boolean;
     /** Class names to be passed to the underlying DOM element */
@@ -51,7 +51,7 @@ function nullIfNever(_value: never): null {
     return null;
 }
 
-export function Block<T extends DocumentBlock>(props: BlockProps<T>) {
+export function Block<T extends SlimDocumentBlock>(props: BlockProps<T>) {
     const { block, style, isEstimatedOffscreen, context } = props;
 
     const content = (() => {
@@ -132,7 +132,7 @@ export function Block<T extends DocumentBlock>(props: BlockProps<T>) {
 /**
  * Skeleton for a block while it is being loaded.
  */
-export function BlockSkeleton(props: { block: DocumentBlock; style: ClassValue }) {
+export function BlockSkeleton(props: { block: SlimDocumentBlock; style: ClassValue }) {
     const { block, style } = props;
     const id = 'meta' in block && block.meta && 'id' in block.meta ? block.meta.id : undefined;
 
diff --git a/packages/gitbook/src/components/DocumentView/Blocks.tsx b/packages/gitbook/src/components/DocumentView/Blocks.tsx
index 903acd2955..f2346b3316 100644
--- a/packages/gitbook/src/components/DocumentView/Blocks.tsx
+++ b/packages/gitbook/src/components/DocumentView/Blocks.tsx
@@ -1,7 +1,6 @@
-import type { DocumentBlock, JSONDocument } from '@gitbook/api';
-
 import { type ClassValue, tcls } from '@/lib/tailwind';
 
+import type { SlimDocumentBlock, SlimJSONDocument } from '@/lib/slim-document';
 import { Block } from './Block';
 import type { DocumentContextProps } from './DocumentView';
 import { isBlockOffscreen } from './utils';
@@ -9,7 +8,7 @@ import { isBlockOffscreen } from './utils';
 /**
  * Renders a list of blocks with a wrapper element.
  */
-export function Blocks<TBlock extends DocumentBlock, Tag extends React.ElementType = 'div'>(
+export function Blocks<TBlock extends SlimDocumentBlock, Tag extends React.ElementType = 'div'>(
     props: UnwrappedBlocksProps<TBlock> & {
         /** HTML tag to use for the wrapper */
         tag?: Tag;
@@ -30,15 +29,15 @@ export function Blocks<TBlock extends DocumentBlock, Tag extends React.ElementTy
     );
 }
 
-type UnwrappedBlocksProps<TBlock extends DocumentBlock> = DocumentContextProps & {
+type UnwrappedBlocksProps<TBlock extends SlimDocumentBlock> = DocumentContextProps & {
     /** Blocks to render */
     nodes: TBlock[];
 
     /** Document being rendered */
-    document: JSONDocument;
+    document: SlimJSONDocument;
 
     /** Ancestors of the blocks */
-    ancestorBlocks: DocumentBlock[];
+    ancestorBlocks: SlimDocumentBlock[];
 
     /** Style passed to all blocks */
     blockStyle?: ClassValue;
@@ -50,7 +49,9 @@ type UnwrappedBlocksProps<TBlock extends DocumentBlock> = DocumentContextProps &
 /**
  * Renders a list of blocks without a wrapper element.
  */
-export function UnwrappedBlocks<TBlock extends DocumentBlock>(props: UnwrappedBlocksProps<TBlock>) {
+export function UnwrappedBlocks<TBlock extends SlimDocumentBlock>(
+    props: UnwrappedBlocksProps<TBlock>
+) {
     const { nodes, blockStyle, isOffscreen: defaultIsOffscreen = false, ...contextProps } = props;
 
     let isOffscreen = defaultIsOffscreen;
@@ -65,11 +66,11 @@ export function UnwrappedBlocks<TBlock extends DocumentBlock>(props: UnwrappedBl
 
         return (
             <Block
-                key={node.key || `${node.type}-${index}`}
+                key={'key' in node && node.key ? node.key : `${node.type}-${index}`}
                 block={node}
                 style={[
                     'mx-auto w-full decoration-primary/6',
-                    node.data && 'fullWidth' in node.data && node.data.fullWidth
+                    'data' in node && node.data && 'fullWidth' in node.data && node.data.fullWidth
                         ? 'max-w-screen-xl'
                         : 'max-w-3xl',
                     blockStyle,
diff --git a/packages/gitbook/src/components/DocumentView/Caption.tsx b/packages/gitbook/src/components/DocumentView/Caption.tsx
index f7649e68a8..b6551ba067 100644
--- a/packages/gitbook/src/components/DocumentView/Caption.tsx
+++ b/packages/gitbook/src/components/DocumentView/Caption.tsx
@@ -3,12 +3,12 @@ import type {
     DocumentBlockEmbed,
     DocumentBlockFile,
     DocumentBlockImage,
-    JSONDocument,
 } from '@gitbook/api';
 
 import { getNodeFragmentByName, isNodeEmpty } from '@/lib/document';
 import { type ClassValue, tcls } from '@/lib/tailwind';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import type { DocumentContextProps } from './DocumentView';
 import { Inlines } from './Inlines';
 
@@ -18,7 +18,7 @@ import { Inlines } from './Inlines';
 export function Caption(
     props: {
         children: React.ReactNode;
-        document: JSONDocument;
+        document: SlimJSONDocument;
         style?: ClassValue;
         fit?: boolean;
         wrapperStyle?: ClassValue;
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/ClientCodeBlock.tsx b/packages/gitbook/src/components/DocumentView/CodeBlock/ClientCodeBlock.tsx
index ede23ee1d4..f1cec9a7b8 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/ClientCodeBlock.tsx
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/ClientCodeBlock.tsx
@@ -1,19 +1,19 @@
 'use client';
 
-import type { DocumentBlockCode } from '@gitbook/api';
 import { useEffect, useMemo, useRef, useState } from 'react';
 
 import { useInViewportListener } from '@/components/hooks/useInViewportListener';
 import { useScrollListener } from '@/components/hooks/useScrollListener';
+import type { SlimDocumentBlockCode } from '@/lib/slim-document';
 import { useDebounceCallback } from 'usehooks-ts';
-import type { BlockProps } from '../Block';
-import { CodeBlockRenderer } from './CodeBlockRenderer';
+import { CodeBlockRenderer, type CodeBlockRendererProps } from './CodeBlockRenderer';
 import type { HighlightLine, RenderedInline } from './highlight';
 import { plainHighlight } from './plain-highlight';
 
-type ClientBlockProps = Pick<BlockProps<DocumentBlockCode>, 'block' | 'style'> & {
+interface ClientBlockProps extends Omit<CodeBlockRendererProps, 'lines'> {
+    block: SlimDocumentBlockCode;
     inlines: RenderedInline[];
-};
+}
 
 /**
  * Render a code-block client-side by loading the highlighter asynchronously.
@@ -24,14 +24,14 @@ export function ClientCodeBlock(props: ClientBlockProps) {
     const blockRef = useRef<HTMLDivElement>(null);
     const isInViewportRef = useRef(false);
     const [isInViewport, setIsInViewport] = useState(false);
-    const plainLines = useMemo(() => plainHighlight(block, []), [block]);
+    const plainLines = useMemo(() => plainHighlight({ block, inlines: [] }), [block]);
     const [lines, setLines] = useState<null | HighlightLine[]>(null);
     const [highlighting, setHighlighting] = useState(false);
 
     // Preload the highlighter when the block is mounted.
     useEffect(() => {
-        import('./highlight').then(({ preloadHighlight }) => preloadHighlight(block));
-    }, [block]);
+        import('./highlight').then(({ preloadHighlight }) => preloadHighlight(block.data.syntax));
+    }, [block.data.syntax]);
 
     // When user scrolls, we need to wait for the scroll to finish before running the highlight
     const isScrollingRef = useRef(false);
@@ -80,7 +80,7 @@ export function ClientCodeBlock(props: ClientBlockProps) {
             if (typeof window !== 'undefined') {
                 setHighlighting(true);
                 import('./highlight').then(({ highlight }) => {
-                    highlight(block, inlines).then((lines) => {
+                    highlight({ block, inlines }).then((lines) => {
                         if (cancelled) {
                             return;
                         }
@@ -104,7 +104,9 @@ export function ClientCodeBlock(props: ClientBlockProps) {
         <CodeBlockRenderer
             ref={blockRef}
             aria-busy={highlighting}
-            block={block}
+            title={props.title}
+            withLineNumbers={props.withLineNumbers}
+            withWrap={props.withWrap}
             style={style}
             lines={lines ?? plainLines}
         />
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlock.tsx b/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlock.tsx
index 2516c8d4ff..aa8f74ec50 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlock.tsx
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlock.tsx
@@ -1,8 +1,7 @@
-import type { DocumentBlockCode } from '@gitbook/api';
-
 import { getNodeFragmentByType } from '@/lib/document';
 import { isV2 } from '@/lib/v2';
 
+import type { SlimDocumentBlockCode } from '@/lib/slim-document';
 import type { BlockProps } from '../Block';
 import { Blocks } from '../Blocks';
 import { ClientCodeBlock } from './ClientCodeBlock';
@@ -12,8 +11,11 @@ import { type RenderedInline, getInlines, highlight } from './highlight';
 /**
  * Render a code block, can be client-side or server-side.
  */
-export async function CodeBlock(props: BlockProps<DocumentBlockCode>) {
+export async function CodeBlock(props: BlockProps<SlimDocumentBlockCode>) {
     const { block, document, style, isEstimatedOffscreen, context } = props;
+    const withLineNumbers = Boolean(block.data.lineNumbers) && block.nodes.length > 1;
+    const withWrap = block.data.overflow === 'wrap';
+    const title = block.data.title ?? '';
     const inlines = getInlines(block);
     const richInlines: RenderedInline[] = inlines.map((inline, index) => {
         const body = (() => {
@@ -38,9 +40,29 @@ export async function CodeBlock(props: BlockProps<DocumentBlockCode>) {
 
     if (isV2() && !isEstimatedOffscreen) {
         // In v2, we render the code block server-side
-        const lines = await highlight(block, richInlines);
-        return <CodeBlockRenderer block={block} style={style} lines={lines} />;
+        const lines = await highlight({
+            inlines: richInlines,
+            block,
+        });
+        return (
+            <CodeBlockRenderer
+                withLineNumbers={withLineNumbers}
+                withWrap={withWrap}
+                title={title}
+                style={style}
+                lines={lines}
+            />
+        );
     }
 
-    return <ClientCodeBlock block={block} style={style} inlines={richInlines} />;
+    return (
+        <ClientCodeBlock
+            block={block}
+            withLineNumbers={withLineNumbers}
+            withWrap={withWrap}
+            title={title}
+            style={style}
+            inlines={richInlines}
+        />
+    );
 }
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlockRenderer.tsx b/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlockRenderer.tsx
index f1f8cb8f63..2ae28f7f1b 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlockRenderer.tsx
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/CodeBlockRenderer.tsx
@@ -12,10 +12,13 @@ import type { HighlightLine, HighlightToken } from './highlight';
 import './theme.css';
 import './CodeBlockRenderer.css';
 
-type CodeBlockRendererProps = Pick<BlockProps<DocumentBlockCode>, 'block' | 'style'> & {
+export interface CodeBlockRendererProps extends Pick<BlockProps<DocumentBlockCode>, 'style'> {
     lines: HighlightLine[];
     'aria-busy'?: boolean;
-};
+    withLineNumbers: boolean;
+    withWrap: boolean;
+    title: string;
+}
 
 /**
  * The logic of rendering a code block from lines.
@@ -24,12 +27,8 @@ export const CodeBlockRenderer = forwardRef(function CodeBlockRenderer(
     props: CodeBlockRendererProps,
     ref: React.ForwardedRef<HTMLDivElement>
 ) {
-    const { block, style, lines, 'aria-busy': ariaBusy } = props;
-
+    const { style, lines, withLineNumbers, withWrap, title, 'aria-busy': ariaBusy } = props;
     const id = useId();
-    const withLineNumbers = Boolean(block.data.lineNumbers) && block.nodes.length > 1;
-    const withWrap = block.data.overflow === 'wrap';
-    const title = block.data.title;
 
     return (
         <div
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/PlainCodeBlock.tsx b/packages/gitbook/src/components/DocumentView/CodeBlock/PlainCodeBlock.tsx
index 9c50b95a0b..b0000cd90c 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/PlainCodeBlock.tsx
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/PlainCodeBlock.tsx
@@ -1,6 +1,6 @@
-import type { DocumentBlockCode, JSONDocument } from '@gitbook/api';
 import { useId } from 'react';
 
+import type { SlimDocumentBlockCode, SlimJSONDocument } from '@/lib/slim-document';
 import { CodeBlock } from './CodeBlock';
 
 /**
@@ -11,7 +11,7 @@ export function PlainCodeBlock(props: { code: string; syntax: string }) {
     const { code, syntax } = props;
     const id = useId();
 
-    const block: DocumentBlockCode = {
+    const block: SlimDocumentBlockCode = {
         key: id,
         object: 'block',
         type: 'code',
@@ -37,7 +37,7 @@ export function PlainCodeBlock(props: { code: string; syntax: string }) {
         })),
     };
 
-    const document: JSONDocument = {
+    const document: SlimJSONDocument = {
         object: 'document',
         data: {},
         nodes: [block],
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.test.ts b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.test.ts
index d330fda941..d4e13d5d08 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.test.ts
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.test.ts
@@ -1,14 +1,19 @@
 import { expect, it } from 'bun:test';
 import type { DocumentBlockCode } from '@gitbook/api';
 
+import { getSlimDocumentBlock } from '@/lib/slim-document';
 import { type RenderedInline, getInlines, highlight } from './highlight';
 
 async function highlightWithInlines(block: DocumentBlockCode) {
-    const inlines: RenderedInline[] = getInlines(block).map((inline) => ({
+    const slimBlock = getSlimDocumentBlock(block);
+    const inlines: RenderedInline[] = getInlines(slimBlock).map((inline) => ({
         inline,
         body: null,
     }));
-    return highlight(block, inlines);
+    return highlight({
+        inlines,
+        block: slimBlock,
+    });
 }
 
 it('should parse plain code', async () => {
@@ -46,31 +51,29 @@ it('should parse plain code', async () => {
 
 it('should parse different code in parallel', async () => {
     await Promise.all(
-        ['shell', 'scss', 'scss', 'css', 'scss', 'yaml'].map(async (syntax) =>
-            highlight(
-                {
-                    object: 'block',
-                    type: 'code',
-                    data: {
-                        syntax: syntax,
-                    },
-                    nodes: [
-                        {
-                            object: 'block',
-                            type: 'code-line',
-                            data: {},
-                            nodes: [
-                                {
-                                    object: 'text',
-                                    leaves: [{ object: 'leaf', marks: [], text: 'Hello world' }],
-                                },
-                            ],
-                        },
-                    ],
+        ['shell', 'scss', 'scss', 'css', 'scss', 'yaml'].map(async (syntax) => {
+            const block: DocumentBlockCode = {
+                object: 'block',
+                type: 'code',
+                data: {
+                    syntax,
                 },
-                []
-            )
-        )
+                nodes: [
+                    {
+                        object: 'block',
+                        type: 'code-line',
+                        data: {},
+                        nodes: [
+                            {
+                                object: 'text',
+                                leaves: [{ object: 'leaf', marks: [], text: 'Hello world' }],
+                            },
+                        ],
+                    },
+                ],
+            };
+            highlight({ block: getSlimDocumentBlock(block), inlines: [] });
+        })
     );
 });
 
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
index eb02b5b928..084b79eac5 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
@@ -1,8 +1,4 @@
-import type {
-    DocumentBlockCode,
-    DocumentBlockCodeLine,
-    DocumentInlineAnnotation,
-} from '@gitbook/api';
+import type { DocumentInlineAnnotation } from '@gitbook/api';
 import {
     type ThemedToken,
     createCssVariablesTheme,
@@ -12,6 +8,7 @@ import {
 import { createJavaScriptRegexEngine } from 'shiki/engine/javascript';
 import { type BundledLanguage, bundledLanguages } from 'shiki/langs';
 
+import type { SlimDocumentBlockCode, SlimDocumentBlockCodeLine } from '@/lib/slim-document';
 import { plainHighlight } from './plain-highlight';
 
 export type HighlightLine = {
@@ -46,8 +43,8 @@ const { getSingletonHighlighter } = createSingletonShorthands(
 /**
  * Preload the highlighter for a code block.
  */
-export async function preloadHighlight(block: DocumentBlockCode) {
-    const langName = getBlockLang(block);
+export async function preloadHighlight(syntax: string | undefined): Promise<void> {
+    const langName = getLanguageFromSyntax(syntax);
     if (langName) {
         await getSingletonHighlighter({
             langs: [langName],
@@ -59,14 +56,16 @@ export async function preloadHighlight(block: DocumentBlockCode) {
 /**
  * Highlight a code block while preserving inline elements.
  */
-export async function highlight(
-    block: DocumentBlockCode,
-    inlines: RenderedInline[]
-): Promise<HighlightLine[]> {
-    const langName = getBlockLang(block);
+export async function highlight(args: {
+    inlines: RenderedInline[];
+    block: SlimDocumentBlockCode;
+    // block: DocumentBlockCode,
+}): Promise<HighlightLine[]> {
+    const { inlines, block } = args;
+    const langName = getLanguageFromSyntax(block.data.syntax);
     if (!langName) {
         // Language not found, fallback to plain highlighting
-        return plainHighlight(block, inlines);
+        return plainHighlight({ inlines, block });
     }
 
     const code = getPlainCodeBlock(block);
@@ -84,7 +83,7 @@ export async function highlight(
 
     let currentIndex = 0;
     return lines.map((tokens, index) => {
-        const lineBlock = block.nodes[index];
+        const node = block.nodes[index];
         const result: HighlightToken[] = [];
 
         const eatToken = (): PositionedToken | null => {
@@ -104,7 +103,7 @@ export async function highlight(
         currentIndex += 1; // for the \n
 
         return {
-            highlighted: Boolean(lineBlock.data.highlighted),
+            highlighted: Boolean(node.highlighted),
             tokens: result,
         };
     });
@@ -113,8 +112,8 @@ export async function highlight(
 /**
  * Get the language of a code block.
  */
-function getBlockLang(block: DocumentBlockCode): string | null {
-    return block.data.syntax ? getLanguageForSyntax(block.data.syntax) : null;
+function getLanguageFromSyntax(syntax: string | undefined): string | null {
+    return syntax ? getLanguageForSyntax(syntax) : null;
 }
 
 const syntaxAliases: Record<string, BundledLanguage> = {
@@ -148,7 +147,7 @@ function getLanguageForSyntax(syntax: string): BundledLanguage | null {
     return null;
 }
 
-export function getInlines(block: DocumentBlockCode) {
+export function getInlines(block: SlimDocumentBlockCode): InlineIndexed[] {
     const inlines: InlineIndexed[] = [];
     getPlainCodeBlock(block, inlines);
 
@@ -237,14 +236,14 @@ function matchTokenAndInlines(
     return result;
 }
 
-function getPlainCodeBlock(code: DocumentBlockCode, inlines?: InlineIndexed[]): string {
+function getPlainCodeBlock(block: SlimDocumentBlockCode, inlines?: InlineIndexed[]): string {
     let content = '';
 
-    code.nodes.forEach((node, index) => {
+    block.nodes.forEach((node, index) => {
         const lineContent = getPlainCodeBlockLine(node, content.length, inlines);
         content += lineContent;
 
-        if (index < code.nodes.length - 1) {
+        if (index < block.nodes.length - 1) {
             content += '\n';
         }
     });
@@ -253,26 +252,32 @@ function getPlainCodeBlock(code: DocumentBlockCode, inlines?: InlineIndexed[]):
 }
 
 function getPlainCodeBlockLine(
-    parent: DocumentBlockCodeLine | DocumentInlineAnnotation,
+    parent: SlimDocumentBlockCodeLine | DocumentInlineAnnotation,
     index: number,
     inlines?: InlineIndexed[]
 ): string {
     let content = '';
 
-    for (const node of parent.nodes) {
-        if (node.object === 'text') {
-            content += cleanupLine(node.leaves.map((leaf) => leaf.text).join(''));
-        } else {
-            const start = index + content.length;
-            content += getPlainCodeBlockLine(node, index + content.length, inlines);
-            const end = index + content.length;
-
-            if (inlines) {
-                inlines.push({
-                    inline: node,
-                    start,
-                    end,
-                });
+    if ('text' in parent && parent.text) {
+        return cleanupLine(parent.text);
+    }
+
+    if ('nodes' in parent && parent.nodes) {
+        for (const node of parent.nodes) {
+            if (node.object === 'text') {
+                content += cleanupLine(node.leaves.map((leaf) => leaf.text).join(''));
+            } else {
+                const start = index + content.length;
+                content += getPlainCodeBlockLine(node, index + content.length, inlines);
+                const end = index + content.length;
+
+                if (inlines) {
+                    inlines.push({
+                        inline: node,
+                        start,
+                        end,
+                    });
+                }
             }
         }
     }
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/plain-highlight.ts b/packages/gitbook/src/components/DocumentView/CodeBlock/plain-highlight.ts
index 5247c14ddc..fa3622bc78 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/plain-highlight.ts
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/plain-highlight.ts
@@ -1,40 +1,54 @@
-import type { DocumentBlockCode } from '@gitbook/api';
-
 import { getNodeText } from '@/lib/document';
 
+import type { SlimDocumentBlockCode } from '@/lib/slim-document';
+import assertNever from 'assert-never';
 import type { HighlightLine, HighlightToken, RenderedInline } from './highlight';
 
 /**
  * Parse a code block without highlighting it.
  */
-export function plainHighlight(
-    block: DocumentBlockCode,
-    inlines: RenderedInline[]
-): HighlightLine[] {
+export function plainHighlight(args: {
+    inlines: RenderedInline[];
+    block: SlimDocumentBlockCode;
+}): HighlightLine[] {
+    const { inlines, block } = args;
     const inlinesCopy = Array.from(inlines);
-    return block.nodes.map((lineBlock) => {
-        const tokens: HighlightToken[] = lineBlock.nodes.map((node) => {
-            if (node.object === 'text') {
-                return {
-                    type: 'plain',
-                    content: getNodeText(node),
-                };
-            }
-            const inline = inlinesCopy.shift();
-            return {
-                type: 'annotation',
-                body: inline?.body ?? null,
-                children: [
+    return block.nodes.map((node) => {
+        const tokens: HighlightToken[] = (() => {
+            if ('text' in node) {
+                return [
                     {
                         type: 'plain',
-                        content: getNodeText(node),
+                        content: node.text,
                     },
-                ],
-            };
-        });
+                ];
+            }
+            if ('nodes' in node) {
+                return node.nodes.map((node) => {
+                    if (node.object === 'text') {
+                        return {
+                            type: 'plain',
+                            content: getNodeText(node),
+                        };
+                    }
+                    const inline = inlinesCopy.shift();
+                    return {
+                        type: 'annotation',
+                        body: inline?.body ?? null,
+                        children: [
+                            {
+                                type: 'plain',
+                                content: getNodeText(node),
+                            },
+                        ],
+                    };
+                });
+            }
+            assertNever(node);
+        })();
 
         return {
-            highlighted: Boolean(lineBlock.data.highlighted),
+            highlighted: Boolean(node.highlighted),
             tokens,
         };
     });
diff --git a/packages/gitbook/src/components/DocumentView/DocumentView.tsx b/packages/gitbook/src/components/DocumentView/DocumentView.tsx
index 724a7f2b05..e5153bfb44 100644
--- a/packages/gitbook/src/components/DocumentView/DocumentView.tsx
+++ b/packages/gitbook/src/components/DocumentView/DocumentView.tsx
@@ -1,7 +1,7 @@
 import type { ClassValue } from '@/lib/tailwind';
-import type { JSONDocument } from '@gitbook/api';
 import type { GitBookAnyContext } from '@v2/lib/context';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import { BlockSkeleton } from './Block';
 import { Blocks } from './Blocks';
 
@@ -39,7 +39,7 @@ export interface DocumentContextProps {
  */
 export function DocumentView(
     props: DocumentContextProps & {
-        document: JSONDocument;
+        document: SlimJSONDocument;
 
         /** Style passed to the container */
         style?: ClassValue;
@@ -73,14 +73,17 @@ export function DocumentView(
 /**
  * Placeholder for the entire document layout.
  */
-export function DocumentViewSkeleton(props: { document: JSONDocument; blockStyle: ClassValue }) {
+export function DocumentViewSkeleton(props: {
+    document: SlimJSONDocument;
+    blockStyle: ClassValue;
+}) {
     const { document, blockStyle } = props;
 
     return (
         <div className="flex flex-col gap-4">
-            {document.nodes.map((block) => (
+            {document.nodes.map((block, index) => (
                 <BlockSkeleton
-                    key={block.key!}
+                    key={block.key ?? `idx-${index}`}
                     block={block}
                     style={[
                         'mx-auto w-full decoration-primary/6',
diff --git a/packages/gitbook/src/components/DocumentView/Images.tsx b/packages/gitbook/src/components/DocumentView/Images.tsx
index baaab50bdc..4db71eb5f7 100644
--- a/packages/gitbook/src/components/DocumentView/Images.tsx
+++ b/packages/gitbook/src/components/DocumentView/Images.tsx
@@ -2,13 +2,13 @@ import type {
     DocumentBlockImage,
     DocumentBlockImageDimension,
     DocumentBlockImages,
-    JSONDocument,
 } from '@gitbook/api';
 
 import { Image, type ImageResponsiveSize } from '@/components/utils';
 import { resolveContentRef } from '@/lib/references';
 import { type ClassValue, tcls } from '@/lib/tailwind';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import type { BlockProps } from './Block';
 import { Caption } from './Caption';
 import type { DocumentContext } from './DocumentView';
@@ -62,7 +62,7 @@ export const imageBlockSizes: ImageResponsiveSize[] = [
 
 async function ImageBlock(props: {
     block: DocumentBlockImage;
-    document: JSONDocument;
+    document: SlimJSONDocument;
     style: ClassValue;
     context: DocumentContext;
     siblings: number;
diff --git a/packages/gitbook/src/components/DocumentView/Inline.tsx b/packages/gitbook/src/components/DocumentView/Inline.tsx
index 9101ffef20..05906f646a 100644
--- a/packages/gitbook/src/components/DocumentView/Inline.tsx
+++ b/packages/gitbook/src/components/DocumentView/Inline.tsx
@@ -7,10 +7,10 @@ import type {
     DocumentInlineLink,
     DocumentInlineMath,
     DocumentInlineMention,
-    JSONDocument,
 } from '@gitbook/api';
 import assertNever from 'assert-never';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import { Annotation } from './Annotation/Annotation';
 import type { DocumentContextProps } from './DocumentView';
 import { Emoji } from './Emoji';
@@ -26,7 +26,7 @@ export interface InlineProps<T extends DocumentInline> extends DocumentContextPr
     /**
      * Document being rendered.
      */
-    document: JSONDocument;
+    document: SlimJSONDocument;
 
     /**
      * Inline ancestors of the current inline.
diff --git a/packages/gitbook/src/components/DocumentView/Inlines.tsx b/packages/gitbook/src/components/DocumentView/Inlines.tsx
index 45200414ce..863d5175e9 100644
--- a/packages/gitbook/src/components/DocumentView/Inlines.tsx
+++ b/packages/gitbook/src/components/DocumentView/Inlines.tsx
@@ -1,5 +1,6 @@
-import type { DocumentInline, DocumentText, JSONDocument } from '@gitbook/api';
+import type { DocumentInline, DocumentText } from '@gitbook/api';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import type { DocumentContextProps } from './DocumentView';
 import { Inline } from './Inline';
 import { Text } from './Text';
@@ -9,7 +10,7 @@ export function Inlines<T extends DocumentInline | DocumentText>(
         /**
          * Document being rendered.
          */
-        document: JSONDocument;
+        document: SlimJSONDocument;
 
         /**
          * Ancestors of the current inline.
diff --git a/packages/gitbook/src/components/DocumentView/ListItem.tsx b/packages/gitbook/src/components/DocumentView/ListItem.tsx
index d290de8074..352bbae04a 100644
--- a/packages/gitbook/src/components/DocumentView/ListItem.tsx
+++ b/packages/gitbook/src/components/DocumentView/ListItem.tsx
@@ -1,5 +1,4 @@
 import type {
-    DocumentBlock,
     DocumentBlockListItem,
     DocumentBlockListOrdered,
     DocumentBlockListUnordered,
@@ -10,6 +9,7 @@ import { assert } from 'ts-essentials';
 import { Checkbox } from '@/components/primitives';
 import { tcls } from '@/lib/tailwind';
 
+import type { SlimDocumentBlock } from '@/lib/slim-document';
 import type { BlockProps } from './Block';
 import { Blocks } from './Blocks';
 import { getBlockTextStyle } from './spacing';
@@ -103,7 +103,7 @@ export function ListItem(props: BlockProps<DocumentBlockListItem>) {
 }
 
 function getListItemDepth(input: {
-    ancestorBlocks: DocumentBlock[];
+    ancestorBlocks: SlimDocumentBlock[];
     type: DocumentBlockListOrdered['type'] | DocumentBlockListUnordered['type'];
 }): number {
     const { ancestorBlocks, type } = input;
diff --git a/packages/gitbook/src/components/DocumentView/OpenAPI/context.tsx b/packages/gitbook/src/components/DocumentView/OpenAPI/context.tsx
index a40411fa6a..b88bd858e2 100644
--- a/packages/gitbook/src/components/DocumentView/OpenAPI/context.tsx
+++ b/packages/gitbook/src/components/DocumentView/OpenAPI/context.tsx
@@ -1,4 +1,3 @@
-import type { JSONDocument } from '@gitbook/api';
 import { Icon } from '@gitbook/icons';
 import type { OpenAPIContext } from '@gitbook/react-openapi';
 
@@ -12,6 +11,7 @@ import { Heading } from '../Heading';
 import './scalar.css';
 import './style.css';
 import type { AnyOpenAPIOperationsBlock, OpenAPISchemasBlock } from '@/lib/openapi/types';
+import type { SlimJSONDocument } from '@/lib/slim-document';
 
 /**
  * Get the OpenAPI context to render a block.
@@ -32,7 +32,7 @@ export function getOpenAPIContext(args: {
         renderCodeBlock: (codeProps) => <PlainCodeBlock {...codeProps} />,
         renderDocument: (documentProps) => (
             <DocumentView
-                document={documentProps.document as JSONDocument}
+                document={documentProps.document as SlimJSONDocument}
                 context={props.context}
                 style="space-y-6"
                 blockStyle="max-w-full"
diff --git a/packages/gitbook/src/components/DocumentView/utils/isBlockOffscreen.ts b/packages/gitbook/src/components/DocumentView/utils/isBlockOffscreen.ts
index 522a47d2b2..fcd3b846a1 100644
--- a/packages/gitbook/src/components/DocumentView/utils/isBlockOffscreen.ts
+++ b/packages/gitbook/src/components/DocumentView/utils/isBlockOffscreen.ts
@@ -1,4 +1,4 @@
-import type { DocumentBlock, JSONDocument } from '@gitbook/api';
+import type { SlimDocumentBlock, SlimJSONDocument } from '@/lib/slim-document';
 import memoize from 'memoizee/weak';
 
 /**
@@ -11,9 +11,9 @@ export function isBlockOffscreen(
         document,
         ancestorBlocks,
     }: {
-        document: JSONDocument;
-        block: DocumentBlock;
-        ancestorBlocks: DocumentBlock[];
+        document: SlimJSONDocument;
+        block: SlimDocumentBlock;
+        ancestorBlocks: SlimDocumentBlock[];
     },
     screenHeight = 500
 ): boolean {
@@ -44,8 +44,8 @@ function getBlockOffset({
     block,
     parent,
 }: {
-    block: DocumentBlock;
-    parent: DocumentBlock | JSONDocument;
+    block: SlimDocumentBlock;
+    parent: SlimDocumentBlock | SlimJSONDocument;
 }): number {
     if (!('nodes' in parent)) {
         return 0;
@@ -66,7 +66,7 @@ function getBlockOffset({
     return offset;
 }
 
-const getBlockHeight = memoize((block: DocumentBlock | undefined): number => {
+const getBlockHeight = memoize((block: SlimDocumentBlock | undefined): number => {
     if (!block) {
         return 0;
     }
@@ -115,6 +115,6 @@ const getBlockHeight = memoize((block: DocumentBlock | undefined): number => {
     }
 });
 
-const getBlockHeights = memoize((blocks: DocumentBlock[]): number => {
+const getBlockHeights = memoize((blocks: SlimDocumentBlock[]): number => {
     return blocks.reduce((total, block) => total + getBlockHeight(block), 0);
 });
diff --git a/packages/gitbook/src/components/PageAside/PageAside.tsx b/packages/gitbook/src/components/PageAside/PageAside.tsx
index a51410cbc0..02687ab8d8 100644
--- a/packages/gitbook/src/components/PageAside/PageAside.tsx
+++ b/packages/gitbook/src/components/PageAside/PageAside.tsx
@@ -1,5 +1,4 @@
 import {
-    type JSONDocument,
     type RevisionPageDocument,
     SiteAdsStatus,
     SiteInsightsAdPlacement,
@@ -14,6 +13,7 @@ import { getSpaceLanguage, t } from '@/intl/server';
 import { getDocumentSections } from '@/lib/document-sections';
 import { tcls } from '@/lib/tailwind';
 
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import { Ad } from '../Ads';
 import { getPDFURLSearchParams } from '../PDF';
 import { PageFeedbackForm } from '../PageFeedback';
@@ -25,7 +25,7 @@ import { ScrollSectionsList } from './ScrollSectionsList';
  */
 export function PageAside(props: {
     page: RevisionPageDocument;
-    document: JSONDocument | null;
+    document: SlimJSONDocument | null;
     context: GitBookSiteContext;
     withHeaderOffset: { sectionsHeader: boolean; topHeader: boolean };
     withFullPageCover: boolean;
@@ -255,7 +255,10 @@ export function PageAside(props: {
     );
 }
 
-async function PageAsideSections(props: { document: JSONDocument; context: GitBookSiteContext }) {
+async function PageAsideSections(props: {
+    document: SlimJSONDocument;
+    context: GitBookSiteContext;
+}) {
     const { document, context } = props;
 
     const sections = await getDocumentSections(context, document);
diff --git a/packages/gitbook/src/components/PageBody/PageBody.tsx b/packages/gitbook/src/components/PageBody/PageBody.tsx
index 6d548dec95..358f45ba18 100644
--- a/packages/gitbook/src/components/PageBody/PageBody.tsx
+++ b/packages/gitbook/src/components/PageBody/PageBody.tsx
@@ -1,4 +1,4 @@
-import type { JSONDocument, RevisionPageDocument } from '@gitbook/api';
+import type { RevisionPageDocument } from '@gitbook/api';
 import type { GitBookSiteContext } from '@v2/lib/context';
 import React from 'react';
 
@@ -6,6 +6,7 @@ import { getSpaceLanguage } from '@/intl/server';
 import { t } from '@/intl/translate';
 import { hasFullWidthBlock, isNodeEmpty } from '@/lib/document';
 import type { AncestorRevisionPage } from '@/lib/pages';
+import type { SlimJSONDocument } from '@/lib/slim-document';
 import { tcls } from '@/lib/tailwind';
 import { DocumentView, DocumentViewSkeleton } from '../DocumentView';
 import { TrackPageViewEvent } from '../Insights';
@@ -21,7 +22,7 @@ export function PageBody(props: {
     context: GitBookSiteContext;
     page: RevisionPageDocument;
     ancestors: AncestorRevisionPage[];
-    document: JSONDocument | null;
+    document: SlimJSONDocument | null;
     withPageFeedback: boolean;
 }) {
     const { page, context, ancestors, document, withPageFeedback } = props;
diff --git a/packages/gitbook/src/lib/api.ts b/packages/gitbook/src/lib/api.ts
index 2bb2039bc3..98d45c3b8f 100644
--- a/packages/gitbook/src/lib/api.ts
+++ b/packages/gitbook/src/lib/api.ts
@@ -29,6 +29,7 @@ import {
     noCacheFetchOptions,
     parseCacheResponse,
 } from './cache';
+import { type SlimJSONDocument, getSlimJSONDocument } from './slim-document';
 
 /**
  * Pointer to a relative content, it might change overtime, the pointer is relative in the content history.
@@ -692,7 +693,7 @@ export const getReusableContent = async (
  * Get a document by its ID.
  */
 export const getDocument = cache({
-    name: 'api.getDocument.v2',
+    name: 'api.getDocument.v3',
     tag: (spaceId, documentId) =>
         getCacheTag({ tag: 'document', space: spaceId, document: documentId }),
     tagImmutable: true,
@@ -710,7 +711,9 @@ export const getDocument = cache({
                 ...noCacheFetchOptions,
             }
         );
-        return cacheResponse(response, cacheTtl_7days);
+        const slimResponse = response as unknown as HttpResponse<SlimJSONDocument, Error>;
+        slimResponse.data = getSlimJSONDocument(response.data);
+        return cacheResponse(slimResponse, cacheTtl_7days);
     },
     // Temporarily allow for a longer timeout than the default 10s
     // because GitBook's API currently re-normalizes all documents
@@ -722,7 +725,7 @@ export const getDocument = cache({
  * Get a computed document.
  */
 export const getComputedDocument = cache({
-    name: 'api.getComputedDocument',
+    name: 'api.getComputedDocument.v2',
     tag: (organizationId, spaceId, source) =>
         getComputedContentSourceCacheTags(
             {
@@ -752,6 +755,8 @@ export const getComputedDocument = cache({
                 ...noCacheFetchOptions,
             }
         );
+        const slimResponse = response as unknown as HttpResponse<SlimJSONDocument, Error>;
+        slimResponse.data = getSlimJSONDocument(response.data);
         return cacheResponse(response, cacheTtl_7days);
     },
     // Temporarily allow for a longer timeout than the default 10s
diff --git a/packages/gitbook/src/lib/document-sections.ts b/packages/gitbook/src/lib/document-sections.ts
index 38619a5881..d0acb51b6a 100644
--- a/packages/gitbook/src/lib/document-sections.ts
+++ b/packages/gitbook/src/lib/document-sections.ts
@@ -1,9 +1,9 @@
-import type { JSONDocument } from '@gitbook/api';
 import type { GitBookAnyContext } from '@v2/lib/context';
 
 import { getNodeText } from './document';
 import { resolveOpenAPIOperationBlock } from './openapi/resolveOpenAPIOperationBlock';
 import { resolveOpenAPISchemasBlock } from './openapi/resolveOpenAPISchemasBlock';
+import type { SlimJSONDocument } from './slim-document';
 
 export interface DocumentSection {
     id: string;
@@ -18,7 +18,7 @@ export interface DocumentSection {
  */
 export async function getDocumentSections(
     context: GitBookAnyContext,
-    document: JSONDocument
+    document: SlimJSONDocument
 ): Promise<DocumentSection[]> {
     const sections: DocumentSection[] = [];
     let depth = 0;
diff --git a/packages/gitbook/src/lib/document.ts b/packages/gitbook/src/lib/document.ts
index 33618f76c1..eef025f6e1 100644
--- a/packages/gitbook/src/lib/document.ts
+++ b/packages/gitbook/src/lib/document.ts
@@ -1,11 +1,6 @@
-import type {
-    DocumentBlock,
-    DocumentFragment,
-    DocumentInline,
-    DocumentText,
-    JSONDocument,
-} from '@gitbook/api';
+import type { DocumentFragment, DocumentInline, DocumentText } from '@gitbook/api';
 import assertNever from 'assert-never';
+import type { SlimDocumentBlock, SlimJSONDocument } from './slim-document';
 
 export interface DocumentSection {
     id: string;
@@ -17,7 +12,7 @@ export interface DocumentSection {
 /**
  * Check if the document contains one block that should be rendered in full-width mode.
  */
-export function hasFullWidthBlock(document: JSONDocument): boolean {
+export function hasFullWidthBlock(document: SlimJSONDocument): boolean {
     for (const node of document.nodes) {
         if (node.data && 'fullWidth' in node.data && node.data.fullWidth) {
             return true;
@@ -34,7 +29,7 @@ export function hasFullWidthBlock(document: JSONDocument): boolean {
  * Get the text of a block/inline.
  */
 export function getNodeText(
-    node: JSONDocument | DocumentText | DocumentFragment | DocumentInline | DocumentBlock
+    node: DocumentText | DocumentFragment | DocumentInline | SlimDocumentBlock | SlimJSONDocument
 ): string {
     switch (node.object) {
         case 'text':
@@ -57,7 +52,7 @@ export function getNodeText(
  * Get a fragment by its type in a node.
  */
 export function getNodeFragmentByType(
-    node: DocumentInline | DocumentBlock,
+    node: DocumentInline | SlimDocumentBlock,
     type: string
 ): DocumentFragment | null {
     if (!('fragments' in node)) {
@@ -71,7 +66,7 @@ export function getNodeFragmentByType(
  * Get a fragment by its `fragment` name in a node.
  */
 export function getNodeFragmentByName(
-    node: DocumentInline | DocumentBlock,
+    node: DocumentInline | SlimDocumentBlock,
     name: string
 ): DocumentFragment | null {
     if (!('fragments' in node)) {
@@ -85,7 +80,7 @@ export function getNodeFragmentByName(
  * Test if a node is empty.
  */
 export function isNodeEmpty(
-    node: DocumentText | DocumentFragment | DocumentInline | DocumentBlock | JSONDocument
+    node: DocumentText | DocumentFragment | DocumentInline | SlimJSONDocument | SlimDocumentBlock
 ): boolean {
     if ((node.object === 'block' || node.object === 'inline') && node.isVoid) {
         return false;
@@ -106,7 +101,7 @@ export function isNodeEmpty(
 /**
  * Get the title for a node.
  */
-export function getBlockTitle(block: DocumentBlock): string {
+export function getBlockTitle(block: SlimDocumentBlock): string {
     switch (block.type) {
         case 'expandable': {
             const titleFragment = getNodeFragmentByType(block, 'expandable-title');
@@ -132,7 +127,7 @@ export function getBlockTitle(block: DocumentBlock): string {
 /**
  * Get a block by its ID in the document.
  */
-export function getBlockById(document: JSONDocument, id: string): DocumentBlock | null {
+export function getBlockById(document: SlimJSONDocument, id: string): SlimDocumentBlock | null {
     return findBlock(document, (block) => {
         if ('meta' in block && block.meta && 'id' in block.meta) {
             return block.meta.id === id;
@@ -145,9 +140,9 @@ export function getBlockById(document: JSONDocument, id: string): DocumentBlock
  * Find a block by a predicate in the document.
  */
 function findBlock(
-    container: JSONDocument | DocumentBlock | DocumentFragment,
-    test: (block: DocumentBlock) => boolean
-): DocumentBlock | null {
+    container: SlimJSONDocument | SlimDocumentBlock | DocumentFragment,
+    test: (block: SlimDocumentBlock) => boolean
+): SlimDocumentBlock | null {
     if (!('nodes' in container)) {
         return null;
     }
diff --git a/packages/gitbook/src/lib/slim-document/blocks/code-line.ts b/packages/gitbook/src/lib/slim-document/blocks/code-line.ts
new file mode 100644
index 0000000000..8b41ebfa3d
--- /dev/null
+++ b/packages/gitbook/src/lib/slim-document/blocks/code-line.ts
@@ -0,0 +1,56 @@
+import type { DocumentBlockCodeLine } from '@gitbook/api';
+
+/**
+ * Common interface for a slim code line.
+ */
+interface SlimDocumentBlockCodeLineCommon
+    extends Omit<DocumentBlockCodeLine, 'nodes' | 'data' | 'key'> {
+    highlighted?: true;
+}
+
+/**
+ * Code line with text only.
+ */
+export interface SlimDocumentBlockCodeLineText extends SlimDocumentBlockCodeLineCommon {
+    text: string;
+}
+
+/**
+ * Code line with annotations.
+ */
+export interface SlimDocumentBlockCodeLineAnnotated extends SlimDocumentBlockCodeLineCommon {
+    nodes: DocumentBlockCodeLine['nodes'];
+}
+
+/**
+ * Slim version of a DocumentBlockCodeLine.
+ */
+export type SlimDocumentBlockCodeLine =
+    | SlimDocumentBlockCodeLineText
+    | SlimDocumentBlockCodeLineAnnotated;
+
+/**
+ * Transform a DocumentBlockCodeLine into a slim version.
+ */
+export function transform(block: DocumentBlockCodeLine): SlimDocumentBlockCodeLine {
+    let hasTextOnly = true;
+    const text = block.nodes.reduce((acc, node) => {
+        if (node.object === 'text') {
+            return acc + node.leaves.map((leaf) => leaf.text).join('');
+        }
+        hasTextOnly = false;
+        return acc;
+    }, '');
+    const slimNode: SlimDocumentBlockCodeLine = hasTextOnly
+        ? { type: block.type, object: block.object, text, isVoid: block.isVoid }
+        : {
+              nodes: block.nodes,
+              type: block.type,
+              object: block.object,
+              isVoid: block.isVoid,
+          };
+    if (block.data.highlighted) {
+        slimNode.highlighted = true;
+    }
+    return slimNode;
+}
diff --git a/packages/gitbook/src/lib/slim-document/blocks/code.ts b/packages/gitbook/src/lib/slim-document/blocks/code.ts
new file mode 100644
index 0000000000..48536682f2
--- /dev/null
+++ b/packages/gitbook/src/lib/slim-document/blocks/code.ts
@@ -0,0 +1,20 @@
+import type { DocumentBlockCode } from '@gitbook/api';
+import { type SlimifyDocumentBlocks, all } from '../util';
+
+/**
+ * Slim version of a DocumentBlock.
+ * We transform the document into a slim version to reduce the size of the data
+ * stored in cache and sent to the client.
+ */
+export interface SlimDocumentBlockCode extends Omit<DocumentBlockCode, 'nodes'> {
+    nodes: SlimifyDocumentBlocks<DocumentBlockCode['nodes']>;
+}
+/**
+ * Transform a code block into a slim version.
+ */
+export function transform(block: DocumentBlockCode): SlimDocumentBlockCode {
+    return {
+        ...block,
+        nodes: all(block.nodes),
+    };
+}
diff --git a/packages/gitbook/src/lib/slim-document/index.ts b/packages/gitbook/src/lib/slim-document/index.ts
new file mode 100644
index 0000000000..f8c399189c
--- /dev/null
+++ b/packages/gitbook/src/lib/slim-document/index.ts
@@ -0,0 +1,35 @@
+import type { DocumentBlock, DocumentBlocksTopLevels, JSONDocument } from '@gitbook/api';
+import { type SlimifyDocumentBlock, all } from './util';
+
+/**
+ * Slim version of DocumentBlocksTopLevels.
+ */
+export type SlimDocumentBlocksTopLevels = SlimifyDocumentBlock<DocumentBlocksTopLevels>;
+
+/**
+ * Slim version of a DocumentBlock.
+ */
+export type SlimDocumentBlock = SlimifyDocumentBlock<DocumentBlock>;
+
+/**
+ * Slim version of a JSON document.
+ */
+export interface SlimJSONDocument extends Omit<JSONDocument, 'nodes'> {
+    nodes: SlimDocumentBlocksTopLevels[];
+}
+
+// Re-export all slim block types.
+export type { SlimDocumentBlockCode } from './blocks/code';
+export type { SlimDocumentBlockCodeLine } from './blocks/code-line';
+
+/**
+ * Transform a document to a slim version.
+ */
+export function getSlimJSONDocument(document: JSONDocument): SlimJSONDocument {
+    return {
+        ...document,
+        nodes: all(document.nodes),
+    };
+}
+
+export { one as getSlimDocumentBlock } from './util';
diff --git a/packages/gitbook/src/lib/slim-document/util.ts b/packages/gitbook/src/lib/slim-document/util.ts
new file mode 100644
index 0000000000..776ea6e7fa
--- /dev/null
+++ b/packages/gitbook/src/lib/slim-document/util.ts
@@ -0,0 +1,50 @@
+import type { DocumentBlock, DocumentBlockCode, DocumentBlockCodeLine } from '@gitbook/api';
+import * as codeBlock from './blocks/code';
+import * as codeLineBlock from './blocks/code-line';
+
+type TransformMap = {
+    [T in DocumentBlock as T['type']]: (block: T) => SlimifyDocumentBlock<T>;
+};
+
+/**
+ * Contains all block transformations.
+ * The key is the block type, and the value is the transform function.
+ */
+const transforms: Partial<TransformMap> = {
+    code: codeBlock.transform,
+    'code-line': codeLineBlock.transform,
+};
+
+/**
+ * Transform any DocumentBlock into a slim version.
+ */
+export type SlimifyDocumentBlock<T extends DocumentBlock> = T extends DocumentBlockCode
+    ? codeBlock.SlimDocumentBlockCode
+    : T extends DocumentBlockCodeLine
+      ? codeLineBlock.SlimDocumentBlockCodeLine
+      : T;
+
+/**
+ * Transform all blocks to a slim version.
+ */
+export function all<T extends DocumentBlock[]>(blocks: T): SlimifyDocumentBlocks<T> {
+    return blocks.map((block) => one(block)) as SlimifyDocumentBlocks<T>;
+}
+
+/**
+ * Transform a block to a slim version.
+ */
+export function one<T extends DocumentBlock>(block: T): SlimifyDocumentBlock<T> {
+    const transform = transforms[block.type];
+    if (transform) {
+        return transform(block as any) as SlimifyDocumentBlock<T>;
+    }
+    return block as SlimifyDocumentBlock<T>;
+}
+
+/**
+ * Transform an array of DocumentBlock into a slim version.
+ */
+export type SlimifyDocumentBlocks<T extends DocumentBlock[]> = {
+    [K in keyof T]: T[K] extends DocumentBlock ? SlimifyDocumentBlock<T[K]> : T[K];
+};