I've had my new G4 iBook for a few weeks now, and I just noticed that it has slowed down in terms of its ability to render graphics in a game. The first night I had the computer, I played Tony Hawk Pro Skater 4 for a while and the graphics were remarkably smooth and didn't hitch at all. Tonight I opened the game for the first time in a while and noticed that the graphics don't display as smoothly and there are occasional hitches. I repair permissions after each software install and run MacJanitor. What happened?