Of course Dirt 2 runs faster in DirectX 11 then DirectX 10 .. seeing as there is no DX10 option iirc.. even at 1FPS it's faster than the 0fps that DX10 yeilds ;-) Haven't seen any new (last week or so) Dirt 2 benchmarks with DX11 vs DX9 but I seem to recall that DX9 was faster then DX11 (
THG Dirt 2 DX 11 vs DX9), on avg at least 30% faster in DX9 vs DX11. Of course things may have changed in last month with updated drivers and such. The results seem to mirror what is at
pcgameshardware - dirt 2 direct x 11 vs direct x 9 benchmarks as well. Of course this is to be expected, given that DX9 has had years to mature, devs becoming increasingly comfortable working with Direct 3D 9.x and that DX11 adds (at a significant penalty) increased visuals.