Regarding 30FPS limits, the somewhat recent extension for Halo CE called Chimera which, among other things, can interpolate animations throughout the game.
Topic on Talk:Halo: Combat Evolved
Isn't this a multiplayer only fix? No way to get a better framerate on singleplayer? If it is then it should be clarified on the wiki.
No. It works for the Custom Edition single-player campaign.