I have a 2.4UMBP with 4Gb DDR3 ram and a 7200rpm hdd. Im on 10.6.2, After i open iMovie 09 and while using it my system becomes very laggy (also some beachballs here and there), why is that? I have nothing else opened. This never happened a few months ago and i don't believe any app is causing this. Thank you for anyone who helps.