I run poser 5 on 233Mhz pentium 2 with only 96 megs of ram, I don't have any of the service releases, and I have never had one problem with stability. Even when I have multiple hi-res characters with tons of props and full background, the firefly renders just as quick for me as the old poser 4, and that's with all the firefly's bells and whistles turned on. (Is that just fluke on my part?)