My computer system has a spec that is a little better than yours is, so when you say that you Render with four persons+ and use upwards of 3 lights and a scene prop, what type of render are you doing? Poser 4 draft, or Production or Poser 5 Firefly or draft any of these conditions will change render times and performance - I'd really like to know how long your renders take with four figures+ since mine take ages.
On a crosstalk note I find a lot of crosstalk problems using the P5 male and V3 and when I use M3 or David and V3, renders are really soooo slow.

I can't make serious comment about P6 yet since I haven't had enough time to work with it but so far I have not encountered any major problems that some people say they are experiencing. My guess is that they are running very low on memory.

PXP