What is the option "Texture Atlas Size" for?

You know I've always wondered this even though I max it out.

I think it's a reference to how much video memory it will use for textures. If you've got a good video card you can raise it. I believe the second number is the reference to the video memory your card actually has. I raised mine to 8000 or whatever and it never accepted it. When I lowered it to 2048 which is how much ram my card has the setting stuck. According to Cari you'll get increased performance by raising it as long as your card can handle it.

I'd really like to know more about this option as well and what the proper configuration should be, and what (if any) the effect actually is (and of course performance implications)