I had upgraded my video card recently (Nvidia GTS-450) and I was having a significant problem with "shimmering" at airports in FSX. That is, the runways and runway lines and markings would "travel" up and down and across the screen, mainly as I was passing by, or approaching, an airport. I finally found the answer to this issue on one of the flight sim websites, which was to activate the Anti-Aliasing-Transparency feature in the Nvidia Control panel. There are various degrees of settings for this feature, "Off", "Multi-sample", "2X supersample", :4X supersample", and "8X supersample". Supposedly, the higher the setting, the more negative effect it has on framerates. However, I set it to "8X supersample", which is the highest setting, and it had little to no effect on my framerates that I could observe. And my CPU is not "high end" but a middle-of-the-road Core i5 750 running at 2.8Ghz. More importantly, the shimmering at the airport was greatly reduced, I would estimate by at least 90 percent. If anyone else, using an Nvidia card, has this problem, give this a try.Bob

You'll find the downside of high transparency anti-aliasing settings when going into clouds or haze together with rain while the normal scenery doesn't cause high loads there. Might be that the 450 starts to struggle then. I prefer transparency anti-aliasing too, it makes the instruments, trees and fences look really good and can be handled on any weather with lower settings or on higher ones with the strong cards.I think mipmaps are also a cause for shimmering textures at some sceneries.

I think mipmaps are also a cause for shimmering textures at some sceneries.

More like the lack of mip maps. Too bad all devs don't take the extra time like FSDT and FT do to mip map all their sceneries.