A developer who will go nameless here has said that Poser is traditionally coded in the CodeWarrior IDE for Mac then ported to PC. In the bid for compatibility and identical results, the code in all likelihood does not have any optimization for any hardware or OS hooks, leaving the efficiency up to the strength of your system. Judging from the hints kupa's been dropping about conforming clothes, gravity and strand-based hair, I'm guessing that Poser 5 is being optimized for both MacOS and Windows to make these features even plausible. I'm not an expert in these things, but I recall Blender's authors being very reliant on open graphics standards like OpenGL to allow them to port from Windows to PocketPC to Linux to OSX. Apparently MacOS 9.x wasn't as OpenGL-friendly. When Curious stops supporting MacOS 9 and its legacy issues and starts reaping the benefits of OSX's graphics engines, I think Mac rendering times will substantially improve. Curious' response along these lines is essentially "we'll wait and see."