Optimize CID lookups to reduce N+1 query pattern in exam review question responses

anatomy/views.py

@@ -287,6 +287,15 @@ def exam_review_question_responses(request, pk: int, q_index: int):
     # candidate try to resolve the CidUser and show CID + name if available. If neither
     # is present fall back to empty/anonymous.
 
+    # Optimize CID lookups: collect distinct CID values and fetch all CidUser rows
+    # in a single query to avoid an N+1 query pattern.
+    cids_qs = exam_user_answers_qs.values_list("cid", flat=True).distinct()
+    cids = [c for c in cids_qs if c is not None and str(c).strip() != ""]
+    cid_map = {}
+    if cids:
+        for cu in CidUser.objects.filter(cid__in=cids):
+            cid_map[cu.cid] = cu
+
     exam_user_answers = []
     for ua in exam_user_answers_qs:
         # default display
@@ -302,9 +311,9 @@ def exam_review_question_responses(request, pk: int, q_index: int):
                 else:
                     name = getattr(user, "username", str(user))
                 display = name
-            elif getattr(ua, "cid", None):
+            elif getattr(ua, "cid", None) is not None:
                 cid_val = ua.cid
-                cu = CidUser.objects.filter(cid=cid_val).first()
+                cu = cid_map.get(cid_val)
                 if cu is not None and cu.name:
                     display = f"CID{cid_val} ({cu.name})"
                 else: