I have the latest patch, and I can play the rest of the game with all settings maxed out, except when I play Lonesome Road, my FPS goes from 45-60 to 25-35 and it's really really annoying. I think it's all the fog/weather/sand storms that is causing it.

Specs -

Windows 7 64-bit

AMD 1055T OCed @3.4ghz
AMD Diamond HD Radeon 6870 OCed @ 950Mhz
Corsair Revenge - 8GB 4gbx2 1600mhz


What setting should I lower to get rid of this lag? (I literally have everything set to high)

Thanks in advance.