I didn't have any real perf. impact because of hairworks, tested it in that benchmark part with those furry animals and on/off basically irrelevant, only lower character detail without it. So im keeping it enabled. I lowered shader detail to ultra instead of max and that seems to be the best balance visual/perf., I think I saw that hardware unboxed perf. review and set accordingly with a bit higher settings here and there@ 1080p.