diff --git a/demo/start.sh b/demo/start.sh
index 470187292..1e591aabb 100755
--- a/demo/start.sh
+++ b/demo/start.sh
@@ -6,7 +6,7 @@ CWD=$(pwd)
 
 cd "$DIR/.."
 
-for port in "8080" "8081" "8082"; do
+for port in 8080 8081 8082; do
     echo "Starting server on port $port... "
 
     python -m synapse.app.homeserver \
@@ -15,7 +15,8 @@ for port in "8080" "8081" "8082"; do
         -f "$DIR/$port.log" \
         -d "$DIR/$port.db" \
         -vv \
-        -D --pid-file "$DIR/$port.pid"
+        -D --pid-file "$DIR/$port.pid" \
+        --manhole $((port + 1000))
 done
 
 echo "Starting webclient on port 8000..."
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 40e3561ee..f210d2662 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -31,6 +31,7 @@ from synapse.api.urls import (
 )
 
 from daemonize import Daemonize
+import twisted.manhole.telnet
 
 import argparse
 import logging
@@ -238,6 +239,8 @@ def setup():
                         default="hs.pid")
     parser.add_argument("-W", "--webclient", dest="webclient", default=True,
                         action="store_false", help="Don't host a web client.")
+    parser.add_argument("--manhole", dest="manhole", type=int, default=None,
+                        help="Turn on the twisted telnet manhole service.")
     args = parser.parse_args()
 
     verbosity = int(args.verbose) if args.verbose else None
@@ -281,6 +284,13 @@ def setup():
 
     hs.build_db_pool()
 
+    if args.manhole:
+        f = twisted.manhole.telnet.ShellFactory()
+        f.username = "matrix"
+        f.password = "rabbithole"
+        f.namespace['hs'] = hs
+        reactor.listenTCP(args.manhole, f, interface='127.0.0.1')
+
     if args.daemonize:
         daemon = Daemonize(
             app="synapse-homeserver",
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index c88cc1878..471dc8616 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -159,12 +159,11 @@ class PresenceHandler(BaseHandler):
         if allowed_by_subscription:
             defer.returnValue(True)
 
-        rm_handler = self.homeserver.get_handlers().room_member_handler
-        for room_id in (yield rm_handler.get_rooms_for_user(observer_user)):
-            if observed_user in (yield rm_handler.get_room_members(room_id)):
-                defer.returnValue(True)
+        share_room = yield self.store.do_users_share_a_room(
+            [observer_user, observed_user]
+        )
 
-        defer.returnValue(False)
+        defer.returnValue(share_room)
 
     @defer.inlineCallbacks
     def get_state(self, target_user, auth_user):
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index a9a09e142..86519b60c 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -150,3 +150,24 @@ class RoomMemberStore(SQLBaseStore):
 
         results = [self._parse_event_from_row(r) for r in rows]
         defer.returnValue(results)
+
+    @defer.inlineCallbacks
+    def do_users_share_a_room(self, user_list):
+        """ Checks whether a list of users share a room.
+        """
+        user_list_clause = " OR ".join(["m.user_id = ?"] * len(user_list))
+        sql = (
+            "SELECT m.room_id FROM room_memberships as m "
+            "INNER JOIN current_state_events as c "
+            "ON m.event_id = c.event_id "
+            "WHERE m.membership = 'join' "
+            "AND (%(clause)s) "
+            "GROUP BY m.room_id HAVING COUNT(m.room_id) = ?"
+        ) % {"clause": user_list_clause}
+
+        args = user_list
+        args.append(len(user_list))
+
+        rows = yield self._execute(None, sql, *args)
+
+        defer.returnValue(len(rows) > 0)