Thank you for this!
I've had the issue since Endwalker as well, and while it feels like the patch fixed it somewhat (ergo no longer constant but only intermittent stuttering during instances), it's not gone. Cutscenes are sometimes fine, sometimes horrible.
Neither the new sound thing helped, nor switching to dx9, not lowering the hz, not changing the headset etc. pp. I tried everything that was put somewhere as a possible fix and nothing helped. I am beyond frustrated that the 6.01 didn't help as I hoped and I would very much appreciate if this would be addressed SOON.