I am seeing this exact same issue after upgrading from 12.04 to 12.10. Compiz and Xorg constantly uses about 5-20% even with little to no user activity and no open windows. I have Nvidia on a Dell with a i7-2720QM with 8GB RAM and the interface is very sluggish. Much slower than 12.04 which was slower than 11.10 on the same system. Let me know if I can help with uploading logs and whatnot.
I am seeing this exact same issue after upgrading from 12.04 to 12.10. Compiz and Xorg constantly uses about 5-20% even with little to no user activity and no open windows. I have Nvidia on a Dell with a i7-2720QM with 8GB RAM and the interface is very sluggish. Much slower than 12.04 which was slower than 11.10 on the same system. Let me know if I can help with uploading logs and whatnot.