I'm exporting a ~2 hour Timeline from Final Cut Pro using compressor, and I figured it would use basically everything I have. I opened Activity monitor, and only ~60% of my processor is idle, and ~1.1 gigs of my 2 gigs of RAM is unused. So what the heck is it doing? Why not use more of the processor or more of the RAM and get the video done quicker? Does it have to do with disk write time?