Add TODO

synapse/handlers/sliding_sync.py

@@ -503,7 +503,9 @@ class SlidingSyncHandler:
         """
         user_id = user.to_string()
 
-        # TODO: Apply filters
+        # TODO: Re-order filters so that the easiest, most likely to eliminate rooms,
+        # are first. This way when people use multiple filters, we can eliminate rooms
+        # and do less work for the subsequent filters.
         #
         # TODO: Exclude partially stated rooms unless the `required_state` has
         # `["m.room.member", "$LAZY"]`