Problems with AE need help.

I have a Macbook Pro that I work from and run the cs5 suite. AE would run perfect on it not too laggy at all nice and smooth. Recently I was having problems and reinstalled the osx to fix it. This is fine and well but when I work in AE now after reinstalling it, it runs like complete garbage.

I can barely get any work done its so horrible, if anyone has any ideas at all of what I can do to get it running smooth again I would be forever in your debt.