Also, I didn't know this before: Hold F3 to show the debug information. It seems it reserves some RAM but only uses some of it at any given time. In my case it had about 700MB in use but was only actively using about 200MB of that.
Takes exactly 10 GB more than your computer has. It would be funny if you were talking about hard drive space. I have a total of just over 3 Terabytes of hard drive space. I'd like to see *anything* use all that. =)
--- Eat well, stay fit, die anyway... Get the message? The best use for Rookies is as "Bullet Sponges"