perf(issues): Fix N+1 queries in starred views endpoint

The starred views serializer was calling serialize() per item, which
triggered separate get_attrs() calls for each starred view — roughly
4N+1 queries for N views. Batch-serialize all views in get_attrs()
instead.

Also adds prefetch_related for the projects M2M and switches
values_list() to .all() so the prefetch cache is actually used.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: scttcper

src/sentry/api/serializers/models/groupsearchview.py

@@ -68,7 +68,7 @@ def get_attrs(self, item_list, user, **kwargs) -> MutableMapping[Any, Any]:
         return attrs
 
     def serialize(self, obj, attrs, user, **kwargs) -> GroupSearchViewSerializerResponse:
-        projects = [-1] if obj.is_all_projects else list(obj.projects.values_list("id", flat=True))
+        projects = [-1] if obj.is_all_projects else [p.id for p in obj.projects.all()]
 
         return {
             "id": str(obj.id),

src/sentry/api/serializers/models/groupsearchviewstarred.py

@@ -3,7 +3,6 @@
 from sentry.api.serializers import Serializer, register, serialize
 from sentry.api.serializers.models.groupsearchview import (
     GroupSearchViewSerializer,
-    GroupSearchViewSerializerResponse,
 )
 from sentry.models.groupsearchviewstarred import GroupSearchViewStarred
 from sentry.models.savedsearch import SORT_LITERALS
@@ -28,13 +27,14 @@ def __init__(self, *args, **kwargs):
         self.organization = kwargs.pop("organization", None)
         super().__init__(*args, **kwargs)
 
-    def serialize(self, obj, attrs, user, **kwargs) -> GroupSearchViewStarredSerializerResponse:
-        serialized_view: GroupSearchViewSerializerResponse = serialize(
-            obj.group_search_view,
+    def get_attrs(self, item_list, user, **kwargs):
+        views = [item.group_search_view for item in item_list]
+        serialized_views = serialize(
+            views,
             user,
-            serializer=GroupSearchViewSerializer(
-                organization=self.organization,
-            ),
+            serializer=GroupSearchViewSerializer(organization=self.organization),
         )
+        return dict(zip(item_list, serialized_views))
 
-        return serialized_view
+    def serialize(self, obj, attrs, user, **kwargs) -> GroupSearchViewStarredSerializerResponse:
+        return attrs

src/sentry/issues/endpoints/organization_group_search_views_starred.py

@@ -31,9 +31,13 @@ def get(self, request: Request, organization: Organization) -> Response:
         """
 
         assert request.user.id is not None
-        starred_views = GroupSearchViewStarred.objects.filter(
-            organization=organization, user_id=request.user.id
-        ).select_related("group_search_view")
+        starred_views = (
+            GroupSearchViewStarred.objects.filter(
+                organization=organization, user_id=request.user.id
+            )
+            .select_related("group_search_view")
+            .prefetch_related("group_search_view__projects")
+        )
 
         return self.paginate(
             request=request,