As I said, I don't really keep up with what is the latest generic FPS game to come out. Just not my thing.
So we know that even at the lowest detail setting you're getting significantly sub-par performance. That is one box to check off in the "not it" column.
Have you checked for any updates to the game itself, and installed those? Maybe poked around the official forums for the game to see if others are having the same problem and if anyone has traced it to a specific update or other issue? People here may be able to offer up some suggestions, but there's nothing quite like someone pissed off as you are, because they can't play a game they want to play, and trying a bunch of things.