diff --git a/synapse/http/client.py b/synapse/http/client.py
index 5b3cefb2dc..8d6e89d6e7 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -20,7 +20,8 @@ import synapse.metrics
 
 from twisted.internet import defer, reactor
 from twisted.web.client import (
-    Agent, readBody, FileBodyProducer, PartialDownloadError
+    Agent, readBody, FileBodyProducer, PartialDownloadError,
+    HTTPConnectionPool,
 )
 from twisted.web.http_headers import Headers
 
@@ -55,7 +56,9 @@ class SimpleHttpClient(object):
         # The default context factory in Twisted 14.0.0 (which we require) is
         # BrowserLikePolicyForHTTPS which will do regular cert validation
         # 'like a browser'
-        self.agent = Agent(reactor)
+        pool = HTTPConnectionPool(reactor)
+        pool.maxPersistentPerHost = 10
+        self.agent = Agent(reactor, pool)
         self.version_string = hs.version_string
 
     def request(self, method, *args, **kwargs):
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 6f976d5ce8..44f0b00333 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -16,7 +16,7 @@
 
 from twisted.internet import defer, reactor, protocol
 from twisted.internet.error import DNSLookupError
-from twisted.web.client import readBody, _AgentBase, _URI
+from twisted.web.client import readBody, _AgentBase, _URI, HTTPConnectionPool
 from twisted.web.http_headers import Headers
 from twisted.web._newclient import ResponseDone
 
@@ -103,7 +103,9 @@ class MatrixFederationHttpClient(object):
         self.hs = hs
         self.signing_key = hs.config.signing_key[0]
         self.server_name = hs.hostname
-        self.agent = MatrixFederationHttpAgent(reactor)
+        pool = HTTPConnectionPool(reactor)
+        pool.maxPersistentPerHost = 10
+        self.agent = MatrixFederationHttpAgent(reactor, pool)
         self.clock = hs.get_clock()
         self.version_string = hs.version_string