I understand your frustration, but it's not exactly a "medium rig" if you just meet the minimum requirements. The 660 is still a capable card, but it's quickly becoming the minimum for new graphically intensive games.

That said, you should probably still be getting better performance than you are. Others seem to be doing so, with similar setups. In addition to hairworks and such, have you already tried turning off the intensive post-processing stuff? You could be playing on low settings with some post-processing effects still on high. Playing at 720p also might also make things smoother, and allow a little more headroom for the settings you want while still looking alright.

Not sure why you're suffering more than others in the area of performance though. Be sure your Nvidia settings aren't mucked up. Someone else already suggested using the nvidia recommended settings via Geforce Experience, but try that.