Does the game runs smooth, or do you suffer low FPS rates? Are the latest drivers for your graphics card installed? Is all input lagged, like you press the movement key, and the character moves a half second later, or only th mouse swing lags etc. OS? Windows, Linux, MAC?
Also, moving this topic to Support.
"One should strive to achieve; not sit in bitter regret." WE ARE NEXUIZ.
Does this lag happen online or in single player? If it's online only, the connection (either end) to the server is not fast enough. If it's in single player, it's NOT lag. You just need to lower the graphical settings of the game.