Hi, after years in this community, I want to tell you something:
1) Modders do work voluntarily and for free for you, so they probably deserve a little respect.
2) "Please" and "thanks" are magic words. "Endorse" is a clickable button.
3) When you treat modders like your servants and just keep asking for something, you only get the modders to stop publishing their work (as many good modders have already done) and you don't get anything.

This is not real mod. It's just a guide how to hide grass or trees. I discovered it thanks to KNGR and his great mod Deserts of Novigrad.

No trees and no grass (it'll give you about 20-30 fps)
Go to YourWitcher3Directory\bin\shaders\speedtree\shaders_directx11 and remove all files except:
Billboard_do_ps.fx11obj
Billboard_ps.fx11obj
Billboard_shadowcast_vs.fx11obj
Billboard_vs.fx11obj

No trees only (it'll give you about 10-20 fps)
Go to YourWitcher3Directory\bin\shaders\speedtree\shaders_directx11 and remove all files except:
Billboard_do_ps.fx11obj
Billboard_ps.fx11obj
Billboard_shadowcast_vs.fx11obj
Billboard_vs.fx11obj
Grass_ps.fx11obj
Grass_shadowcast_ps.fx11obj
Grass_shadowcast_vs.fx11obj
Grass_vs.fx11obj

No grass only (it'll give you about 10 fps)
Go to YourWitcher3Directory\bin\shaders\speedtree\shaders_directx11 and remove:
Grass_ps.fx11obj
Grass_shadowcast_ps.fx11obj
Grass_shadowcast_vs.fx11obj
Grass_vs.fx11obj

Just some trees (it'll give you only about 5-10 fps, but it looks very nice especially in Toussaint)
Go to YourWitcher3Directory\bin\shaders\speedtree\shaders_directx11 and remove:
facing_leaves_ps.fx11obj
facing_leaves_shadowcast_ps.fx11obj
facing_leaves_shadowcast_vs.fx11obj
facing_leaves_vs.fx11obj
FacingLeaves_ps.fx11obj
FacingLeaves_shadowcast_ps.fx11obj
FacingLeaves_shadowcast_vs.fx11obj
FacingLeaves_vs.fx11obj

Backup files are in download section.

I discovered another good trick to reduce image tearing if you don't want to compromise on your claims in graphic setting.In user.settings (In Documents), manually edit FPSLimit=48. Witcher 3 just loves 48 fps. :-D (in game you will see fps set to Unlimited - do not change this, if you change that, you will need to edit user.settings again)

Use this: No Trees No Collisions

My mods for Severance: Blade of Darkness

My mods for Witcher 3

My mods for DoW Soulstorm

Big thanks to CD PROJEKT RED and Andrzej Sapkowski for best games and best novels in this world.
Also thanks to:
www.nexusmods.com for www.nexusmods.com
Sarcen for his awesome W3Edit
xtcislove for his Quick Modding Tool V2.1
my employer for money
my girlfriend for patience with me
and my cat for her cuteness