Comment 9 for bug 1394204

I'm unable to reproduce this issue at home. It could be that it has to do with the sheer number of access-points in your location, which obviously would cause more updates to LastSeen timestamp for each accesspoint, and more AP changes signals.

Is NetworkManager itself spinning? It would be useful to have an excerpt of top; as well as a full debug log for NetworkManager when this happens. A strace of NetworkManager could be useful too, since dbus-daemon speaks to a lot more applications.

To enable debugging in NetworkManager, edit the /etc/init/network-manager.conf file and add to the exec NetworkManager line:
--log-level=debug --log-domains=CORE,WIFI,WIFI_SCAN