The only thing medium is ground textures. Everything else is maxed and on. And I'm not staring at the ground too often at 5000m
But generally, if someone is getting good performance and someone else is not with 2 very comparable systems, the reason doesn't always have to be software. It's little stuff like reg edits. True clean installs etc, that can and will make all the difference in the world.
Edit: @ furbs, high to med ground textures are hardly noticable! Mine looks like all the fancy screen shot stills, except it looks like that 100% of the time live flying
Like I said, I wanted 60FPS all the time and no stutters. 1650x1050 with 8x AA still looks amazing.