Moddim

Just wondering if anyone else is getting rather bad frame rate lag on certain maps in multiplayer big team battle and the multiplayer game menus. Frame rate on one map in particular in big team battle is so bad at times I cannot even move my retical. When cycling through players at the score screen my game lags so bad my xbox stutters, freezes and makes horrid noises. Ragnarok seems to be the only big map that does not lag to the point of hindering my experience. This xbox has never lagged at all in any previous Halo or any other game, though maybe this game is different? Any tips would be great.