From what I can tell, I hitch when going into ADS mode, with much longer hitches the first time a session I use a particular optics/reticle.
I did have to go down from ultra in the settings. Sub 20 FPS when you're used to 40-60 is awful. Taking it down to med upped to 100-120 fps and CPU bound, but dear god the quality is awful. On my system high is also CPU bound, but is back in the 40-60 range.
Shame I can't stand medium, I was clearly winning fights I normally lose (as to be expected with how the engine conflates damage and frame rate.)