Ok, this topic is just a suggestion.

I have seen on the forum of France-VFR (they make payware photo-realistic sceneries) that a lot of people are actually getting better FPS while displaying those FS9 textures on those sceneries.

I suggest those of you who have FSX make a try about importing some BIG addon scenes and post their results. I am talking about scenes that actually replace completely the ground textures, so that one gets rid of the heavy default textures for that area.

BTW, if FS9 is still installed on your disk with some addon sceneries, in FSX you can directly declare those sceneries by pointing to them in the FS9 folders

I don't think that the scenery is compatible. The autogen is too dense on FSX, I get trees and rivers on the taxiways and runways, when I try to install scenery on FSX from FS9.