You sure your GPU powerful enough for it?

First of all, what resolution are you playing in?
Even on 1280x1024, 6670 still kinda lack the power to run on acceptable FPS.

PS: Wrong section as well.

yes, gaming resolution?
crysis not a light game.

i think ur gc driver problem.. try update ur driver..

crysis warhead is old 2008 games..6670 is enough for it..

mine q8300 plus 5750 play crysis 2 at 1900x1080 maxed out oso can smooth..

Can you list down your full system specifications?

Make sure AA is off.

I suspect the lag is due to a weak graphic card. Crysis Warhead is quite a demanding game and still is today. What you could do is like what Firagaz mentioned, reduce or switch off the AA / AF settings entirely as these are known performance hitters. You could download a software called Fraps and it can help monitor what FPS you're getting.

If you see the bench below for HD 5750 (i couldn't find HD 6670, the HD 5750 is slightly faster though), it can only churn out 17.7 min FPS under 1680 x 1050 resolution, which is basically unplayable.

http://www.anandtech.com/bench/Product/537

  i try play crysis  semua siri    with apu3850 ok je smooth   med spec
patch update x?
back ground program   mybe kacau kot... mcm anti vilus..  bla2 sofware  yg run autostart with window..

Main problem, JACK SPARROW OR ORI?

Most likely. 
@TS: Can you monitor the CPU usage during games?

Change to hd6770.

Wonder some forumer here said smooth on their sytem even tough using "basic pc" summore using hd5750 also got "smooth" playing Crysis on 1080p reso.. 

Can u guy give me how u measure "smoothness" that all we talking about? Somehow i feel ridiculous seeing this.. 

Honestly using hd6670, hd5750 or any below these level gc sure can't get smooth over Crysis under 1080P reso.. Because Crysis and Crysis Warhead one of tough graphical game..

PS: No offense here.. Peace..

The terms of "smooth" i think is very different for everyone. FPS around 30+- might look smooth for awhile, but for me, i still will lower the setting to get higher fps.

I agree that fps above 40 is better for game play. At least you can felt that your pc not that tough to handle your game.

Even with a single 5870, everything max out, i still found that a slightly lag while running or in the middle of war. I only able to get 30+- for max out setting crysis/ crysis warhead. This game is graphic hunger.

Actually, FPS is quite a subjective experience. But from my personal experience with games (after so many years), i find that "smooth" gameplay occurs only if you can hit roughly above 40 FPS. In fact, Guru3D also summarized very clearly here. I've tried gaming with a HD 6670 at full 1080p resolution on Rage, and it churns out around 25 - 30 FPS, which to me is still playable but i find it laggy at times. Definitely not the "smooth" that i'm looking for.

try reinstall the game xD

Try 800x600, low setting.