Shubb, have you tried turning off sound and USB to see if that reduced your CPU load? Testing on a friends 3.0 demo: * Fresh start of XP, no running apps: parallels uses 13% (V2.5 uses ~11%), But it is quite variable. * Windowserver goes up to 100% use once in a while, OS X mouse (outside the VM) loses control / jumps about. Cannot use OS X at all while this happens, even app switching stops working. * Paused and hidden, Parallels uses 2.6% CPU (V2.5 I got down to 1.3% with turning sound support off). Generally performance is not too great in my very cursory 2nd-hand experience -- just playing an MP3 for example shot CPU up to ~48% in the host!!!