Ouch. I don't think I can beat a 439MB image file. I can come up with several other files in excess of 1 GB. They're either sound or video, however, and they're uncompressed.

If you're working with files *that* big, then 512MB is not enough. Go up to 1GB of memory, and you should see a nice speed boost as Windows won't have to do anywhere near enough swapping.