@cyanide202: Thanks but in my first post I did mention that alt-f2 does not help. It require a full logout/in to recover.
@remoulder: I have done, it doesn't appear to be CPU load related. At times just typing can be hard, things become so unresponsive for spurts, then you end up with 20 letter 't's etc, very frustrating. It does seem to me that the frequency of this is less often now, but still troubling.