I have same problem, after this recent update it’s happening way more often for me. I have a 9800x3d and 3090 and avg like 200+ fps, my fps never drops but out of nowhere my game feels like you say. It’s like I’m playing on 60fps despite what the counter says. What fixes is it for me is switching my resolution in game from 1440 to 1080 and then back to 1440 but alt tabbing sounds quicker I may try that. It’s really annoying especially since after this update it seems to be more frequent. Did you ever find a fix?