Are you using XP and want to go to very high without downloading anything? well its easy! All you have to do is go to Program files/electronic arts/Crytek/Crysis/bin32, then find these 2 DLLs
make cryrenderD3D9 to CryrenderD3D10 and change CryrenderD3D10 to cryrenderD3D9. Then rightclick on the EXE and create a shortcut. go to properties and at the end of the patch type -DX10.