The bobbing is unavoidable as far as I'm aware, and to disable it would probably be considered cheating anyway. It's part of that realism factor. If you want to drop one setting, I recommend shadows. Medium and high make little difference so try dropping it to low. Or try disabling hbao as it is a bit of a performance hit. Personally, I think you'd benefit from the eye candy more than a few extra frames when you already have very good fps, and regardless of framerates, you're still going to be affected by lag etc that will make your gameplay less smooth anyway.