Fps drop and jump

[desolace1 1]

Hi i bought dayz yestarday but i have a problem with fps. Normally i have 20-90 fps it's huge difference and i'm experiencing fps jumps. It depends on when i move camera, for example i can stay and look around, and i see: 90, 50, 30, 60, 90, 20, 40 fps. I tried to put all on low but there is no much difference between low or high. All time i have huge fps jumps and drops to ~20fps and i feel little lags. All other games works properly, i checked temperatures and made few diagnose tests, and there are no problems with my pc. My friends have older pc than mine and they have no problems with fps. Any tips? I'll be very grateful.

-Win 7 64bit 
-8 GB RAM 
-Intel Core i5-3450S, 2.80GHz 
-AMD Radeon HD 7870 

[SaveMeJebus 164]

2.8 ghz processor is unfortunately on the weak side for running this atm.  More optimizations will(should) be made later on down the road and hopefully will get better but as for now even with an OC'd i5-3570k at 4.3 ghz I still see pretty wild fluctuations in fps.  Also quite a few of the graphics settings when dropped to low will offload from the gpu and make the cpu work harder hitting your fps even more, even tho it seems wrong most settings will work best if set to normal so the gpu still manages them.