Its very hard for halo to be laggy because they have dedicate servers to just the multiplayer aspect of the game. im gonna have to go with grondaivors statement in saying that it is probably your connection. check your nat settings and other things having to do with your connection firewall, provider, etc..... or if your using a wireless link move your router up away from other electronic devices, and away from the floor
My Gaming all started Back when i was a little kid. Playing lion king on the sega. who would have ever guessed that it would lead to dominating on the Gears of war and Halo Franchises. As well as many other titles.