Thanks !
I tried it (lite version) and it worked, although I've got a problem that required uninstallation.
Let me explain... Hopefully someone will step in and provide his/her experience.
TL;DR : not sure it worked at first, my FPS were the same in the end ; also had to uninstall but don't know why.
Here's what I did :
1. installed the mod and cleaned up the shader cache (both in terrain and saved games/fxo, saved games/metashaders2)
2. started up the game with MSAAx2 (previously I didn't use MSAA) and after about 20 minutes (yeah that's long) it generated almost 400 metashader files for 140MB, then started
3. noticed that FPS were good, as good as without MSAA before ; decided to crank up MSAA to x4 ; noticed that the mod was up (I think) because of a black ring around the FOV in the 2D screen mirror (but not in the HMD)
4. modified the setting, restarted the game
5. waited (main loading screen) forever, the log saying that a few shaders needed recompiling (having a MSAA4 in their name so I gathered it was because of the MSAA change)
6. gave up after 10 minutes with no progress whatsoever (nothing in the log, no change in the shader files)
7. restarted : same difference
8. reset to MSAAx2 : again, stuck
9. deleted all metashaders and restarted : stuck
10. got back to no mod and cleared shaders : worked after a few seconds
11. tried MSAAx2 without the mod : does not change FPS significantly.
Any idea what went wrong ?
Was the mod correctly installed ?