GFX optimization with HD7850 (choppy movement)

[nealius]

Hey guys, it's been a while since I've flown FSX. I recently built a rig specifically for sims like DCS: A-10 and Falcon BMS 4.32, and I figured it would work fairly well with FSX but it seems I thought wrong. My system specs are as follows:

AMD Phenom II X4 965BE 3.4GHz
ATI HD7850 2GB stock
8GB DDR3 RAM
750W PSU

I made the autogen tweaks in the fsx.cfg file (set both to 800 trees/buildings per cell), and I've been messing around with the graphics sliders but the only thing that seems to effect performance is "high resolution cockpit textures," which doesn't make sense to me because Falcon BMS 4.32 uses double resolution cockpit textures and it runs fine. Mesh resolution/complexity has a little effect on performance, but I honestly have no clue what the "mesh" is.

Does anyone have some tips regarding ATI cards?

EDIT

Ok, so, running out of Kimpo in Seoul I'm getting around 50-55fps, which is good, BUT, movement is extremely choppy.