Some have over 100 hours!
Might as well get into the game properly now, get everything out of the way and be ready for the next DLC stuff.
Running most things on high, I think the main things are:
particle detail - high
ambient occ. - ultra (HBAO+ looks nice and doesn't impact performance too much but it creates shadows on objects when it shouldn't)
all shadows settings - high
the object and distance sliders - about 50%
DOF, lens flare, CA - off (don't like these effects)
post fxaa - off (can't see any jaggies tbh)
volumetric fog - medium
Average FPS outside is about 44 and inside, locked to 60. There is nothing that can be reduced to get much higher FPS outside without massively impacting IQ. This game feels nice and smooth unlike other games at 40-50 fps though.
If you haven't got a free/g sync screen, mess around with vsync option + FPS locks and nvidia control panel vsync options. For me, locking FPS to 60 via AMD crimson and having the vsync option "on" in game seems the best.