PSA : to all people having stutter issues "recently" or "since stormblood".

Check that windows 10 hasn't engaged the "game mode" for FFXIV.

I spent countless hours reinstalling drivers, changing pieces of hardware only to find out that small piece of shit was doing the stutter.

Disable game mode for FFXIV in xbox/dvr app, then turn game mode completely off in settings => games => game mode.