Read about it here: http://www.tweakguides.com/Crysis_8.html


While Crysis has many in-game options for adjusting visual quality and performance, and we've covered these in detail in the In-Game Settings section, fortunately that's not where the tweaking stops. The CryEngine2 game engine powering Crysis is extremely customizable, and there are a large number of parameters which can be adjusted to further alter the image quality and performance of the game. There are three main ways to tweak Crysis variables: using the in-game command console; by editing configuration (.cfg) files; and via the command line of the Crysis launch icon. This section of the guide covers both how to use these methods correctly, and a range of the most useful variables which can help you conduct advanced tweaking to suit your needs.

I must stress that advanced tweaking requires thought, patience and effort; there are no quick fixes here so please read all the instructions on this page carefully before proceeding.