Whenever you set the launcher to "Close on game startup" or something similar, it still keeps up a task called "javaw.exe" that isn't your game. There's two in my task manager. One is the actual game, using about 40% processor power, and 1G RAM. The other one is javaw.exe, seems to close the launcher if I delete it. It, depending on the amount of command blocks I'm triggering, uses between 10 and 40% processor power. I can delete the task without any crashes, except that it boosts my performance by about 50%...