diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 557701d0c4..4410cd9e62 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -18,7 +18,6 @@ from synapse.api.errors import StoreError
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.util.caches.dictionary_cache import DictionaryCache
 from synapse.util.caches.descriptors import Cache
-from synapse.util.caches import intern_dict
 from synapse.storage.engines import PostgresEngine
 import synapse.metrics
 
@@ -356,9 +355,9 @@ class SQLBaseStore(object):
         Returns:
             A list of dicts where the key is the column header.
         """
-        col_headers = list(column[0] for column in cursor.description)
+        col_headers = list(intern(column[0]) for column in cursor.description)
         results = list(
-            intern_dict(dict(zip(col_headers, row))) for row in cursor.fetchall()
+            dict(zip(col_headers, row)) for row in cursor.fetchall()
         )
         return results
 
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index b357f22be7..ed84db6b4b 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -25,7 +25,7 @@ logger = logging.getLogger(__name__)
 
 # Remember to update this number every time a change is made to database
 # schema files, so the users will be informed on server restarts.
-SCHEMA_VERSION = 40
+SCHEMA_VERSION = 41
 
 dir_path = os.path.abspath(os.path.dirname(__file__))
 
diff --git a/synapse/storage/schema/delta/41/device_outbound_index.sql b/synapse/storage/schema/delta/41/device_outbound_index.sql
new file mode 100644
index 0000000000..62f0b9892b
--- /dev/null
+++ b/synapse/storage/schema/delta/41/device_outbound_index.sql
@@ -0,0 +1,16 @@
+/* Copyright 2017 Vector Creations Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CREATE INDEX device_lists_outbound_pokes_stream ON device_lists_outbound_pokes(stream_id);