I have a dual core computer, 4 gig of ram etc..... running mix buss on master, drums, toms, overheads, guitar, vocals, bass busses + channel strips on guitars, vocals, bass, and most of the drums. On top of that I have a shit load of other plugs, and it is running about 80%. Very usuable, but still cpu hungry. Remember I only have offline oversampling, if I put online oversampling on I can not have that many instances. The guys over at gearslutz have oversampling on to the max I assume (cause their computers are way better than mine and they can only get a few instances running). It is cpu hungry but nothing like the waves art saturation plug