Interesting findings about DX10 - no flickering and no crashes with 8800

Well, this is what happened to me when I tried out DX10 with my 8800GTS...No flickering of runway textures, no menu crashes, no nothing, stable as a rock.BUT..no performance increase either.. Something interesting I noticed, and perhaps you can help me with this: When using DX10, it seems like FSX is not doing any kind of mipmapping at all, and performance seems to suffer from that...I feel that if I can get DX10 to do some mipmapping then I could get a performance increase relative to DX9!!Does anyone have any ideia why this is happening? Other than that, everything seems ok with DX10!Thanks