About the same as P4 running in classic. Not bad at all, actually. The cloth room crashes every time I try to do anything in it. And the Pose room crashes whenever you do a copy/paste in the animation window. Sometimes the Pose room crashes when just trying to reposition a camera. I haven't tried any of the other rooms yet. I guess the one nice thing about it running in OS X is that you don't have to reboot classic every time Poser crashes. Just hit the save keys every minute or so and you don't lose too much work. It's just when I get really into working a scene that I forget to save and that's when I get "schooled" again.