Lag in games with 80-150 fps [in singkeplayer]

I'm getting decent fps in games but there is still a little bit of lag even in singleplayer games. My gpu and cpu arent overheating and my voltages are all how they are supposed to be. idk if its my screen being retarded or something or what. my screen resolution is 1024x768(i know i need a new one its the next thing im buying). I wanna know if its my gpu or my cpu malfunctioning. It's getting really annoying. In bf3 i get 80-150 fps in singleplayer with everything maxed and i still get stuttering and lag. Help is appreciated. Thanks