At the moment, I believe CraftBukkit, like the Mojang distributed server software, only uses one core. Excepting something something about dump files and such, but that's not too important. Now, I'm no expert or anything, but what is stopping CraftBukkit from supporting two, three, or four cores? I'd love to utilize all of my cores to improve server performance. Is it simply a matter of changing the base mechanics would be too much of a b**** to do without lagging behind and not releasing new versions in a timely manner? Is it because it simply isn't possible for some reason? It would be wonderful to have CraftBukkit running on all four of my cores. I think my server performance would jump up a good deal, especially once under stress.