This sounds like essentially the same as bug 813409 but we won't be sure until (unless?) a fix is developed. In that bug I noted:
"Found the cause to be that my indicator-datetime is set to display seconds, not just hours and minutes. This seems to cause unity/compiz to send the SyncOne and SyncGeometries dbus messages to unity-panel-service every second. And profiling unity-panel-service with callgrind shows it is spending all it's time in g_variant_ fuctions, invoked by the dbus activity. So this needs to be optimized. It's quite wrong that something happening only once per second should use so much CPU."
This sounds like essentially the same as bug 813409 but we won't be sure until (unless?) a fix is developed. In that bug I noted:
"Found the cause to be that my indicator-datetime is set to display seconds, not just hours and minutes. This seems to cause unity/compiz to send the SyncOne and SyncGeometries dbus messages to unity-panel-service every second. And profiling unity-panel-service with callgrind shows it is spending all it's time in g_variant_ fuctions, invoked by the dbus activity. So this needs to be optimized. It's quite wrong that something happening only once per second should use so much CPU."