My computer has more then enough requirements to play call of duty but for some reason when I download the torrent it is very laggy. Is a disk better or is it the same?
Torrents often have corrupted data, they are uploaded by other users and are no a legit copy of the game. Do expect problems with them.
Lag is a measurement related to your internet connection to the server, if you are playing online.
torrented copies can have problems properly connecting and maintain a good connection to the server. But the better chances are is your internet provider either sucks or you are just too far physically to the server in which case there is nothing that can be done.
If you are playing single player and notice a "lag" or choppiness in the game, this is most likely due to setting being too high for your system to handel. Try lowering the settings, if the choppiness remains the same then it's probably something wrong with the game data. Buying and using a retail copy of the game will solve this problem. Or you can risk illegally downloading a different torrent and hoping for something that wont harm your computer and works properly.