Something to chime in since i just tested a few things.
Some settings seem to be completely borked and they probably dont “exist” which cause many issues.
i7 6700K@4.4Ghz/GTX 970.
1)Vertical Sync = On is working the same way as Half, it drops my FPS from 130-140 while testing stuff at End of Time to 72.
Vertical Sync Half, does the same, something completely broken with vertical sync.
2)Putting everything to Very low, makes my game stutter like crazy on certain areas, putting everything to Medium, stops all sorts of stutter apart from when many things happen on the screen and the fps goes from 70 to sub 20, where its a momentary stutter as expected.
Particularly if i recall the Shadows Setting at Very Low seems to be one of the settings that cause this.
Hell even everything on Ultra gives decent FPS and setting shadows at Very Low makes the stutter start, this at that Lake map in Act 2.
3)There seems to be a mega buggy overlap of settings between Master Settings and Individual settings, and overlapping/forcing of the Master settings system.
4)Each map seems to react completely differently to settings.
Pier/Ship map, Master/Texture/Shadows Ultra, rest a mix of Very Low/Off/Medium, steady 60 FPS, Desert map, less than 5 minutes after, same settings, insane stuttering everywhere between 40-60 FPS.
Lowering everything from Ultra to Medium reduced the stutter by 50% averagely, but it never disappeared in the desert map.
Something is fundamentally wrong with the game settings and their overlapping