diff --git a/external-import/sekoia/src/connector/sekoia.py b/external-import/sekoia/src/connector/sekoia.py
index bdfc2aabd82..ff933e2795b 100644
--- a/external-import/sekoia/src/connector/sekoia.py
+++ b/external-import/sekoia/src/connector/sekoia.py
@@ -31,6 +31,7 @@ def __init__(self, config: ConfigLoader, helper: OpenCTIConnectorHelper):
         self.helper = helper
 
         self._cache = {}
+        self._max_identity_cache_size = 5000
         self.duration_period = self.config.connector.duration_period
 
         # Extra config Sekoia
@@ -427,6 +428,11 @@ def _clean_and_add_to_cache(self, item):
         ):
             if item["id"].startswith("marking-definition--"):
                 item.pop("object_marking_refs", None)
+
+            # Apply cache size limit with FIFO eviction
+            if len(self._cache) >= self._max_identity_cache_size:
+                # Remove oldest entry
+                self._cache.pop(next(iter(self._cache)))
             self._cache[item["id"]] = item
 
     def _send_request(self, url, params=None, binary=False):
@@ -532,20 +538,29 @@ def _add_sources_to_items(self, items: List[Dict]):
         for item in items:
 
             labels = []
+            label_names = []
+            source_refs_to_fetch: List[str] = item.get("x_inthreat_sources_refs", [])
+            for source_ref in item.get("x_inthreat_sources_refs", []):
+                if source_ref in self._cache:
+                    source = self._cache[source_ref]
+                    labels.append(f'source:{source["name"]}'.lower())
+                    source_refs_to_fetch.remove(source_ref)
+
             for source in self._retrieve_by_ids(
-                item.get("x_inthreat_sources_refs", []), self.get_object_url
+                source_refs_to_fetch, self.get_object_url
             ):
-                label_name = f'source:{source["name"]}'.lower()
+                labels.append(f'source:{source["name"]}'.lower())
+
+            for label_name in labels:
                 if label_name not in self.all_labels:
                     self._create_custom_label(label_name, "#f8c167")
+                label_names.append(label_name)
 
-                labels.append(label_name)
-
-            if labels:
+            if label_names:
                 if item.get("x_opencti_labels", []):
-                    item["x_opencti_labels"].extend(labels)
+                    item["x_opencti_labels"].extend(label_names)
                 else:
-                    item["x_opencti_labels"] = labels
+                    item["x_opencti_labels"] = label_names
             object_list.append(item)
 
         return object_list