I was thrilled with Aperture's speed when I first started using it, but things ground to a halt when I started shooting all RAW (files are now 15-18MB each). I now get hung up waiting for Aperture to render thumbnails all the time, something it seems to do again and again in the same projects. Is there anything I can do to speed things up? If it there is a software solution, great. If it's mainly a hardware issue, then what's my bottleneck, exactly? I'm running it on a MBP 2.4GHz (Penryn) with 4MB RAM. The hard drive I'm using is an external 7200rpm USB 2 drive.