As tempting as it is to make your PC sweat, if you’re having performance issues, it’s worth sacrificing a bit of graphical fidelity. The obvious temptation is to lower the resolution, but we’d avoid that unless you absolutely have to. Your monitor is designed to work at a specific resolution, and the performance boost of stepping it down usually isn’t worth the loss of picture quality. Instead, tone down the effects. Switch Anti-Aliasing to either 2x or off, turn anisotropic filtering down, and switch Shadows off entirely. These are by far the biggest performance drains. If you need a little more speed, set Texture Filtering to just Bilinear.
Even if you don’t plan to play like this (and trust us, it will look hideous), there’s a reason to strip things down – to see if there’s a more fundamental problem with your system. If not, or once you’ve fixed it with a later tip, you can crank them back up again and see CODBLOPS the way it was meant to be.