afaik it makes the game use lower quality effects on objects past a certain distance. the setting changes how far away the fading starts. --- "The Internet: where women are men, men are women, and little girls are the FBI."
Enabling it grabs several frames. I can notice no difference between them. Stuff that looked nice at a distance before still looks nice, stuff that looked like crap at a distance still looks like crap.
I leave it on. --- http://img41.imageshack.us/img41/4062/lightningrocks.gif