I have a 2010 13" MBP. 2.4GHz. 4GB ram. When working in iMovie things always seem a little laggy. Like pressing the space bar to play, there is always a delay before it actually starts. And when dragging clips in it's definitely less than smooth. Is this a CPU thin or a RAM thing or neither. Just wondering if I'd see some improvement bumping up to 8GB of RAM or if not, what the problem might be if any.