I've had 20 fully clothed full resolution figures in a scene, but not that many props in that scene. Also done a scene with 13 dressed full res figures plus 16 lo res figures and plenty of other stuff, Terradome 2 plus about 35 trees. The UI does tend to slow down, but you can always change to one of the other preview render styles which speeds things up. All of this applies to poser 11 and the pro versions of old poser version. Poser 10 was only 32 bit so you could run out of memory and cause poser to crash. Did this when first got poser 10, think I got up to about 30 to 35 nude figures before the crash.