I think I'm having the same thing going on. This isnt only a personal problem, when tunring the camera the fps goes from 50 to 35(in cities for example), after letting the camera rest the fps will stabilize back to 50 after 2-3secs, it makes the game unplayable with mouse and keyboard. My CPU i7 6700HQ is at 95-100% all the time so the issue definitely realtes to the weakness of my processor. I ususally experience these CPU problems only with Ubisoft games though, shadow of war for example runs extremely fluid 60+ with a CPU usage of barely 50%