I had that problem as well,some few updates ago. After the last couple of updates, my system has started running the graphics remarkably better. I can still get the real bright hanger floor and runway white out, but only with both shadows and post lighting disabled. Since the shadows don't make as big a hit to my FPS I no longer need to disable both settings. This works about the same if I keep post lighting on and disable shadows. If I disable shadows only,and leave post lighting on, or vice versa, I do have to make a 1 notch adjustment to my gamma setting though to offset any over bright/dark object.