diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 249217e114..545d3d3a99 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -129,7 +129,7 @@ class RoomMemberStore(SQLBaseStore):
         with self._stream_id_gen.get_next() as stream_ordering:
             yield self.runInteraction("locally_reject_invite", f, stream_ordering)
 
-    @cached(max_entries=100000, iterable=True)
+    @cached(max_entries=500000, iterable=True)
     def get_users_in_room(self, room_id):
         def f(txn):
 
@@ -274,13 +274,13 @@ class RoomMemberStore(SQLBaseStore):
 
         return rows
 
-    @cached(max_entries=5000)
+    @cached(max_entries=500000, iterable=True)
     def get_rooms_for_user(self, user_id):
         return self.get_rooms_for_user_where_membership_is(
             user_id, membership_list=[Membership.JOIN],
         )
 
-    @cachedInlineCallbacks(max_entries=50000, cache_context=True, iterable=True)
+    @cachedInlineCallbacks(max_entries=500000, cache_context=True, iterable=True)
     def get_users_who_share_room_with_user(self, user_id, cache_context):
         """Returns the set of users who share a room with `user_id`
         """