Ok, so i figured out how do fix most of the lag on Black Ops. First, lower all of your video settings to the lowest it can go. This will help most people but in the cases where you have the worst possible processer and video card on your PC simply run the game in safe mode. To access safe mode for Call of Duty Black Ops and MW2 for that matter, start the game, then go to Task Manager(ctl+alt+delete), go to processes and find Black Ops MP(for MW2 it will be IW4MP) right click on it then click end process. a window will pop up saying are you sure.... bla bla bla. Then, the next time you start the game it will ask you would you like to start the game in safe mode? Click yes and then ALAKAZAM!!!! almost all of your video related lag is completely gone. And you only need to do this once. just dont change any video settings, or it will revert back to regular play.
HAVE A LAG FREE GAME!!!!
REMEMBER, WHEN IN DOUBT, SHUT THE HELL UP, AND UL BE FINE
lol what is the reason to play the game at lowest posible graphics when i have GTS450 AND Intel i5 3.06 GHz? i have no lag anyway. it lags sometimes becouse of the internet connection or becouse of some high ping players in the server.