That sounds like a personal problem, with your xbox. You should try pushing your TV and xbox cords firmly into your devices, and then see if the game fixes. I've encountered a few drops in FPS, and my xbox completely froze and crashed once, but only because I set off a massive TNT cannon whilst playing on 3-person splitscreen.
My xbox has crashed about 4 times in this update , 3 times on split screen ... It's pretty laggy ... Even in 1 player mode ... How does stuff like this get through Alpha & Beta testing ?
Technically, we're in Beta Testing now... they did the alpha testing before the PSExperience and before cert testing... You can bet there were a lot worse bugs than these that they have already caught and fixed before we ever got a chance to see it. But Alpha Testing never really pushes the boundaries and limits quite the same way that Beta Testing does... Usually because your Alpha Testers are (usually) more the Game Developer types than they are Hard Core Players/Fans of the Game.
4J actually relies on this as part of the official debugging process... otherwise it would take much much longer to roll out updates because things would just get delayed in testing.