Thanks for the replies. Bram, I did install KDE and I did restart after updating, although this is the first time I have logged into KDE since the update..
Xavier, that is interesting. It seems to be a problem with KDE 4.2, surely they would have fixed it with KDE 4.2.1? I never have had this problem before when I was using KDE 4.2. In short my CPU usage will not go below around 50% and keeps jumping up to 95%-100% a lot of the time.
