I say nay to hairworks, IF you have an old gpu.
I'm running constant 60 FPS with my settings. Using i5 4460 ; gtx 970 ; RAM:8GB
First of all, Hairworks isn't that much of an improvement for me. It looks nice, yes, but you won't notice the absense once you disable it. Geralt was designed with a lot of love for detail.
On a side note, I play with the short ponytail haircut from the dlc's, so if you don't use the standart long hair, Hairworks is useless.
I'll be running through my settings with short comments:
Ambient Occulsion: NVIDIA HBAO+ (if you're using an nvidia card)
Anti Aliasing (AA): ON (you could tweak the settings in the files if you want 2x, 4x or 8x, but I think 2x is enough)
Bloom: ON (looks nice, no FPS drop)
Depth of field: OFF (looks nice for screenshots, but not for combat. save some FPS with this off)
Detail Level: ULTRA (you want this to be on highest. essential)
Borderless Window Mode: ON (with patch 1.05 you can alt+tab now and W3 was designed to run best in borderless window)
Foliage visibility range: MEDIUM (NOTE!: setting this on ultra eats a lot of FPS Geforce experience sets this on high/ultra by default! DON'T set it that high, unless you got a high end GPU. Medium is enough for running around woods imo)
Grass density: MEDIUM (just like Foliage, you don't need that much grass, unless you want to make screenshots. medium is the best choice)
Light Shafts: ON (you won't loose any FPS by activating it, so if you like it, activate it)
Number of background characters: MEDIUM (IMPORTANT: Nvidia sets this to High, although they don't exactly know the impact. I experience a bit of FPS drop with high settings in big cities, so MEDIUM is recommended)
Texture: ULTRA
Shadows: ULTRA
Water: ULTRA
Terrain detail: ULTRA
These last 4 ones are the most important, so you gotta tweak the others to make them work correctly.