When things start going slow for me, because I have a lot of figures in a scene, I go through the figures, and delete unused morphs. I don't think this helps rendering much, but it seems to speed up posing, and moving around in the posing window. It also reduces the size of the PZ3 files, and seems to make loading and saving faster.

LMK

Probably edited for spelling, grammer, punctuation, or typos.