I've made huge scenes that used a variety of figures, but plenty of Vickys and Mikes. I don't know how a mac compares to a pc as far as cpu and video card we have the same memory. I do get plenty of slow down. I've had hair also slow down my scene, though it was a figure too. I think that figures need more memory in that they have rigging and morphs and Sasha has plenty of morphs. It sounds like you're using most of the tricks I know, except don't have 'enhance multilayer transparency' checked.

Another thing you can do for a crowd is to pose small groups of people in separate scenes and then parent them to a grouping prop or a primitive and import them all into your background scene. Use box tracking to position them in the new scene. Basically, with my last story, I said I didn't care. If I wanted 40 people in a scene, I was going to do it and suffer the delays.

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