Quote - There was also almost no difference between the Core 2 Duo and Core 2 Quad processors machines (both ran at 2.4 Ghz); the extra cores didn't seem to make much of a difference.

Note that under firefly/poser, large parts of the rendering time is wasted in stuff like loading textures from disk, calculating shadow maps etc and these are all single core operations. So try a scene with no shadows, no textures and lot's of polygons... this should give you a better idea of your CPU performance, instead of being bound to HDD performance or something.

And make sure you are using 4 threads on a quad core.