Xcode won't release memory?

Xcode seems to eat up more and more ram the longer it stays open. It gets slower and slower to do mundane things like save a file, until I have to quit it to get it to release that memory. It’s becoming very annoying having to close my project, quit Xcode, watch a dashboard widget and wait for the memory to free up, reopen Xcode, and reopen my project again.

What is Xcode doing with all that ram? Even when I’m only adding comments to an AppleScript file it does this, and I haven’t done a single build all morning. Right now it’s sitting at 394MB. I’m on a 2GB Intel iMac.