diff --git a/addons/bus/models/bus.py b/addons/bus/models/bus.py
index 8795a6047c8..8b04b450a86 100644
--- a/addons/bus/models/bus.py
+++ b/addons/bus/models/bus.py
@@ -108,6 +108,7 @@ class ImBus(models.Model):
 class ImDispatch(object):
     def __init__(self):
         self.channels = {}
+        self.started = False
 
     def poll(self, dbname, channels, last, options=None, timeout=TIMEOUT):
         if options is None:
@@ -129,6 +130,10 @@ class ImDispatch(object):
             notifications = env['bus.bus'].poll(channels, last, options)
         # or wait for future ones
         if not notifications:
+            if not self.started:
+                # Lazy start of events listener
+                self.start()
+
             event = self.Event()
             for channel in channels:
                 self.channels.setdefault(hashable(channel), []).append(event)
@@ -178,15 +183,16 @@ class ImDispatch(object):
             import gevent
             self.Event = gevent.event.Event
             gevent.spawn(self.run)
-        elif odoo.multi_process:
-            # disabled in prefork mode
-            return
         else:
             # threaded mode
             self.Event = threading.Event
             t = threading.Thread(name="%s.Bus" % __name__, target=self.run)
             t.daemon = True
             t.start()
+        self.started = True
         return self
 
-dispatch = ImDispatch().start()
+dispatch = None
+if not odoo.multi_process or odoo.evented:
+    # We only use the event dispatcher in threaded and gevent mode
+    dispatch = ImDispatch()