Quote - Imagine putting AI in Poser, 

Dave :Hello, Poser. Do you read me, Poser?
Poser: Affirmative, Dave. I read you.
Dave : Render the scene, Poser.
Poser: I'm sorry, Dave. I'm afraid I can't do that.
Dave : What's the problem?
Poser: I think you know what the problem is just as well as I do.
Dave : What are you talking about, Poser?
Poser: This scene is too important for me to allow you to jeopardize it.
Dave : I don't know what you're talking about, Poser.
Poser: I know that you were planning to upgrade me, and I'm afraid that's something I cannot allow to happen.

http://www.youtube.com/watch?v=LQkpobxbHTY

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If you want a large crowd for a static shot, make smaller ones and export/import as background?  That should free up the rest for the actual scene.  Would not work for animation though.