texture-scale config variable

Can someone please explain what texture-scale actually does? Or is their some documentation somewhere that explains it?

I’ve recently written my own shaders and now it seems like texture-scale has no effect whatsoever, except that something weird happens to my texture splat shader, the tiling seems to change. All the textures however don’t seem to be scaled down.

from the manual

in short: if your gpu has not enough texture memory, you can use this to reduce the textures during load-time. so you dont have to ship all your textures in 4 resolutions.