There is a separately moderated SketchyPhysics forum. The main moderator is SP's creator; Chris Phillips and the usual helpers are very responsive. http://forums.sketchucation.com/viewforum.php?f=61 I have zero MAC experience, so I can't help there. However, since you are an SU newbie, tackling SP will be a steeper learning curve than it already is. Now I am not quite clear on what you are trying to do. You say you have 2 scenes with 150 tweens. To me that is 150 scenes, and that is not small. Are you trying to create a separate view per frame of video? If so that is overkill depending on your Quicktime frame-rate but I'm guessing here. You may want to post a few JPG extracts of your model, or perhaps the model itself, here or at SketchyPhysics and we can better discern how to optimize it.