There is a gamesave modifier (perhaps it's Modio, I don't recall) that let's you set switches in a gamesave you transfer to your USB stick to remove things like fire rate limiter and give you infinite health regen. If you use that, you should be able to blast through the game relatively quickly. There are a bunch of other features in it, too. Definitely worth looking into.
Pro tip: You can find gamesaves for CoD:WaW that start you in the zombie stages. Then you can modify things like run speed, fire rate, jump height, etc. to have just a boatload of fun. Had a lot of fun with friends back in the day, and would highly recommend it.