diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index 7346206bb..b98900731 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -241,6 +241,16 @@ class ApplicationService(object):
     def is_exclusive_room(self, room_id):
         return self._is_exclusive(ApplicationService.NS_ROOMS, room_id)
 
+    def get_exlusive_user_regexes(self):
+        """Get the list of regexes used to determine if a user is exclusively
+        registered by the AS
+        """
+        return [
+            regex_obj["regex"]
+            for regex_obj in self.namespaces[ApplicationService.NS_USERS]
+            if regex_obj["exclusive"]
+        ]
+
     def is_rate_limited(self):
         return self.rate_limited
 
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 7f04d5668..386d7bed8 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -251,9 +251,7 @@ class RulesForRoom(object):
                 if not self.is_mine_id(user_id):
                     continue
 
-                if self.store.get_if_app_services_interested_in_user(
-                    user_id, exclusive=True
-                ):
+                if self.store.get_if_app_services_interested_in_user(user_id):
                     continue
 
                 # If a user has left a room we remove their push rule. If they
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 0e9e8d345..532df736a 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import re
 import simplejson as json
 from twisted.internet import defer
 
@@ -36,19 +37,31 @@ class ApplicationServiceStore(SQLBaseStore):
             hs.config.app_service_config_files
         )
 
+        # We precompie a regex constructed from all the regexes that the AS's
+        # have registered for exclusive users.
+        exclusive_user_regexes = [
+            regex.pattern
+            for service in self.services_cache
+            for regex in service.get_exlusive_user_regexes()
+        ]
+        if exclusive_user_regexes:
+            exclusive_user_regex = "|".join("(" + r + ")" for r in exclusive_user_regexes)
+            self.exclusive_user_regex = re.compile(exclusive_user_regex)
+        else:
+            # We handle this case specially otherwise the constructed regex
+            # will always match
+            self.exclusive_user_regex = None
+
     def get_app_services(self):
         return self.services_cache
 
-    def get_if_app_services_interested_in_user(self, user_id, exclusive=False):
-        """Check if the user is one associated with an app service
+    def get_if_app_services_interested_in_user(self, user_id):
+        """Check if the user is one associated with an app service (exclusively)
         """
-        for service in self.services_cache:
-            if service.is_interested_in_user(user_id):
-                if exclusive:
-                    return service.is_exclusive_user(user_id)
-                else:
-                    return True
-        return False
+        if self.exclusive_user_regex:
+            return bool(self.exclusive_user_regex.match(user_id))
+        else:
+            return False
 
     def get_app_service_by_user_id(self, user_id):
         """Retrieve an application service from their user ID.
diff --git a/synapse/storage/push_rule.py b/synapse/storage/push_rule.py
index 65bad3fad..0a819d32c 100644
--- a/synapse/storage/push_rule.py
+++ b/synapse/storage/push_rule.py
@@ -163,7 +163,7 @@ class PushRuleStore(SQLBaseStore):
         local_users_in_room = set(
             u for u in users_in_room
             if self.hs.is_mine_id(u)
-            and not self.get_if_app_services_interested_in_user(u, exclusive=True)
+            and not self.get_if_app_services_interested_in_user(u)
         )
 
         # users in the room who have pushers need to get push rules run because