If I open GPO studio on my P4 (4.3G speed, 2G RAM), even with nothing at all happening (no sounds loaded and no midi input) it shows around 8% processor usage. I figured it must be the reverb, so I set the processor/quality thing to 1% AND hit bypass: no change.
Just for comparison, running full Kontakt with nothing going on shows no CPU activity, as expected.
This is normal. I haven't been able to get CPU usage with Studio below 8%. When using Bidule, the program that Studio is derived from, I can get 5%. I'm not sure what the difference is though. I haven't had a chance to compare other VST hosts yet (V-Stack, Chainer, etc.) but would like to at some point.