I'm not getting most of these performance issues people are having with the campaigns, I must be extremely lucky, or a bunch of these technical issues happen in co-op splitscreen or online. All campaigns in their update forms all run brilliantly for me, between 50-60fps throughout. Only noticed a few minor issues...
1. Projectiles in cutscenes sometime look choppy, and some of the character models chug a little when they move in Halo CE.
2. A noticeable framerate dip for the first few seconds of gameplay at the beginning of some of Halo 4's mission.s
3. Got the "Untasked build" error on Halo 4 when loading up 1 mission.