Heh, yeah, it's a big game for sure.
It's no worse than any of at least a few dozen others I have on my PC. It did always end up with a bit of swapping on my MacBook when I only had 4GB of RAM in it, but so did everything else, because running OS X with that little RAM and not closing
everything before you run something big is just asking for trouble. It's a very RAM-hungry OS and always has been. Should be fine now that I'm up to 8, though, just haven't tried. On the other hand, I've never noticed it swap angrily on my desktop. Never did when I had 4GB, and it certainly doesn't now that I have 12.