Noticing more and more weird stuff.
There's a significant, regular stutter that is unaffected by framerate. Even when framerate is perfectly fixed, you can notice the movement isn't smooth at all.
Just strafe looking the grass in front of you and you can see the movement is far from smooth. Again even if the fps counter is showing no frames being dropped at all.
Then, it seems the actual stuttering that happens when you move around, seems mostly fixed by going in the config files and change this:
DisableLoadingMip0="0"
Setting this to 1 seems to reduce significantly the stuttering, but I'm not sure what effect it has. It's possible that it prevents the game from loading mipmaps, meaning that textures go from better resolution to lower resolution in a harsher way.
But it's barely noticeable and if it fixes the stuttering well worth the side-effect.