diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 4e62a84b2897060c3c85c1b26c3a6fd95cfb4357..dd9ee406a1d8c1ecfef57bea30f6e3aae8c5b4e2 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -34,6 +34,8 @@ from synapse.util.manhole import manhole
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
 
+from synapse import events
+
 from twisted.internet import reactor, defer
 from twisted.web.resource import Resource
 
@@ -151,6 +153,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     database_engine = create_engine(config.database_config)
 
     if config.notify_appservices:
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index 9fccc73db39941a845f21464b258643a4aa53c95..0086a2977ec67a5ace2942e477a4ae36debbf207 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -41,6 +41,8 @@ from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
 from synapse.crypto import context_factory
 
+from synapse import events
+
 
 from twisted.internet import reactor, defer
 from twisted.web.resource import Resource
@@ -165,6 +167,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     database_engine = create_engine(config.database_config)
 
     tls_server_context_factory = context_factory.ServerContextFactory(config)
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index 1f5ae1937ec111f1b5e2fd00daeba74b516b7c1b..b5f59a99312c59d83e8dd806ee204700cef3d52c 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -39,6 +39,8 @@ from synapse.api.urls import FEDERATION_PREFIX
 from synapse.federation.transport.server import TransportLayerServer
 from synapse.crypto import context_factory
 
+from synapse import events
+
 
 from twisted.internet import reactor, defer
 from twisted.web.resource import Resource
@@ -156,6 +158,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     database_engine = create_engine(config.database_config)
 
     tls_server_context_factory = context_factory.ServerContextFactory(config)
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 6e5ec01c6c299528978357f3599dc406275dfb2a..44c19a1bef6cb657ada6dfd97ed4fd46628ecfbe 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -41,6 +41,8 @@ from synapse.api.urls import (
 )
 from synapse.crypto import context_factory
 
+from synapse import events
+
 
 from twisted.internet import reactor, defer
 from twisted.web.resource import Resource
@@ -162,6 +164,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     database_engine = create_engine(config.database_config)
 
     tls_server_context_factory = context_factory.ServerContextFactory(config)
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index 1a6f5507a98873f2f7f044af799ffb431af4a119..a0e765c54fb4b4b2375bfe9c63c93550e5b078aa 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -36,6 +36,8 @@ from synapse.util.manhole import manhole
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
 
+from synapse import events
+
 from twisted.internet import reactor, defer
 from twisted.web.resource import Resource
 
@@ -239,6 +241,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     if config.start_pushers:
         sys.stderr.write(
             "\nThe pushers must be disabled in the main synapse process"
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 64b209ffe6279ddbd8b2df0aa231ed3ebf5ae9cf..bf1b995dc2dfc06bdb4850d47516bc5188d5e0ca 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -446,6 +446,8 @@ def start(config_options):
 
     setup_logging(config.worker_log_config, config.worker_log_file)
 
+    synapse.events.USE_FROZEN_DICTS = config.use_frozen_dicts
+
     database_engine = create_engine(config.database_config)
 
     ss = SynchrotronServer(