Just wanted to come back to this and say while I checked and didn’t have any addons besides ublock that should be helping (with many of the extra lists checked/enabled in settings), I do have tampermonkey with these scripts and maybe they’re helping:
Simple Sponsor Skiper YouTube CPU Tamer by AnimationFrame YouTube HD YouTube polymer engine fixes YouTube Web Tweaks YouTube(Chinese characters) YouTube AD Blocker
Along with some others that I don’t think would apply.