I completed Warhead a few days ago, which was a bit on the short side for me. I must admit however that the engine has been better optimised to run with lower spec systems. I ran it with the settings mostly turned up to gamer (high) with one a couple of my favourites (post processing, textures, etc.) turned up to enthusiast (very high). Running @ 1680x1050 with no AA/AF i was getting rougly 27-35FPS according to FRAPS, however this was with my graphics card overclocked a bit (721Mhz Core Clock/933Mhz Memory BUS). With AA on however, my system still gets pwned.
If I used the same settings in the first Crysis i would have usually gotten on average about 20-25FPS. This performance gain i think is mainly due to the reduced draw distance when objects/textures are being rendered, but its well worth the extra frames.