I meet the minimum requirements. Intel Core i5-3210M, NVIDIA GT 650M 2GB, 6GB DDR3 RAM, Crucial M4 256GB & Windows 8 Pro 64bit. I have latest driver 314.07.

Even on all lowest at native resolution 1366x768 I can't get the game to run smooth. Framerate is all over the place and constantly low. I even tried overclocking my GPU to no avail.

I installed the beta and that played AT HIGH SETTINGS AT 40FPS!!! The final single player campaign has FAR FAR worse performance. Under half the performance I had in the beta. This is unacceptable!

What can I do? Is there a patch in the works to improve performance?

I don't blame you. I agree that the Beta ran much better than the final version although they were almost the same in terms of optimisation.

I have a GTX 570 1.25GB everything on lowest settings and v-sync off, even when configuring cvar i get average 40fps maybe 50-60 for a few seconds (ive even seen it go 20fps for a short period)...

It's still unplayable though, because on a game like crysis 3 if you have 30fps and they have 60fps get prepared to get a few wounds and bruises...

It's not my GPU thats the problem.
I actually sent it off 2weeks ago because i thought something was wrong with it but it came back and after testing they said it was working fine...