diff --git a/src/Http/Controllers/Api/AnnotationCandidateController.php b/src/Http/Controllers/Api/AnnotationCandidateController.php
index 788865c..a7b8e2b 100644
--- a/src/Http/Controllers/Api/AnnotationCandidateController.php
+++ b/src/Http/Controllers/Api/AnnotationCandidateController.php
@@ -57,7 +57,7 @@ public function index($id)
             ->with('label');
 
         $yieldItems = function () use ($query): \Generator {
-            foreach ($query->lazy() as $item) {
+            foreach ($query->lazy(10000) as $item) {
                 $item->makeHidden('label_id');
                 yield $item;
             }
@@ -114,6 +114,11 @@ public function indexSimilar($id, $id2)
                 yield $item->id;
             }
 
+            // Return early to avoid running the very expensive query below.
+            if ($query->clone()->count() === $job->annotationCandidates()->count()) {
+                return;
+            }
+
             // Add IDs of candidates without feature vectors at the end.
             $remainingIdsQuery = $job->annotationCandidates()
                 ->whereNotIn('id', function ($query) use ($job) {
diff --git a/src/Http/Controllers/Api/TrainingProposalController.php b/src/Http/Controllers/Api/TrainingProposalController.php
index 8665013..4eadcb3 100644
--- a/src/Http/Controllers/Api/TrainingProposalController.php
+++ b/src/Http/Controllers/Api/TrainingProposalController.php
@@ -55,7 +55,7 @@ public function index($id)
             ->orderBy('id', 'desc');
 
         $yieldItems = function () use ($query): \Generator {
-            foreach ($query->lazy() as $item) {
+            foreach ($query->lazy(10000) as $item) {
                 yield $item;
             }
         };
@@ -111,6 +111,11 @@ public function indexSimilar($id, $id2)
                 yield $item->id;
             }
 
+            // Return early to avoid running the very expensive query below.
+            if ($query->clone()->count() === $job->trainingProposals()->count()) {
+                return;
+            }
+
             // Add IDs of candidates without feature vectors at the end.
             $remainingIdsQuery = $job->trainingProposals()
                 ->whereNotIn('id', function ($query) use ($job) {