try the speed test on both your setups, 'shadows on' speeds up my mac with this test, then it stays at around 56.6 f/s with or without shadows in V8 http://forums.sketchucation.com/viewtopic.php?f=72&t=20076&hilit=speed+test#p166898 john

I have received a response from the SU team; they were able to reproduce the error and comfirmed the bug: "Thank you for your note. I've opened your file and was able to reproduce the crash when draping on the two scenerios you provided where the drape was onto exploded geometry. When draping onto a grouped surface it would work fine and if I grouped the geometry on your two "exploded target" sections those would also drape fine. The issue seems to be specific to what you're draping on and whether or not its a group when I perform the operation in SketchUp 8." It seems to me that if you group the "target" object it helps... sometimes.