The plot thickens...
It seems that the problem only occurs when I am running:
Bitgem + Doubloons + JunkCoin + Powercoin.
If I close any one of these cpu usage drops to 2 - 7% but when I re-open it cpu usage immediately jumps back to 100% and stays there.
I can run:
Bitcoin + Litecoin + LQC + PPC + TRC + FRC + BQC + RUC + TBX + FBX + BTE + Chrome + QT-Creator + Bitvise SSH +MSE and I still don't reach 100%, but if I close ALL of those and run only Bitgem + Doubloons + JunkCoin + Powercoin I get 100% cpu usage instantaneously. Something is up with these clients.
If you are using windows, check the task manager and see which application is causing the problem. You may need to check the processes tab as well.