Hello dear people. I have a few issues with the game graphic, especially vegetations. I'm trying to tweak the config files, but I need some little help.

What's the value that lets me decide how far the game must stream everything? And which is the one that lets me decide how much grass, trees and flowers must pop out in that zone?

For example, let's say that I want the game to stream very little vegetations in a certain amount of feet/metres.

[Rendering/SpeedTree]
GrassDistanceScale= [Ultra value: 1]
GrassGenerationEfficiency= [Default value: 0.075] - Increases amount of grass when value reduced

I think there's much more than that. If anyone knows how all those configuration work, please share the knowledge.

Check this nVidia Tweak Guide, you'll find the information you seek there.
http://www.geforce.com/whats-new/guides/the-witcher-3-wild-hunt-graphics-performance-and-tweaking-guide#the-witcher-3-wild-hunt-tweaking