My Front Row had been running really slow for quite some time now, and since the most recent QuickTime update it had become completely unusable. Browsing the Movies section in particular was super-slow and would hang for 30 seconds to several minutes. I ended up removing a bunch of QuickTime components (like DivX and others) and installed Perian in their place. It was really easy and comes with almost any codec you could want. Now Front Row is running very nicely, and even the DVD playback has improved.