More good news Drtooth, you're still not alone, I'm having those stop-and-go and 144 problems again today.
You know what's annoying about this new player though? When you want to adjust the playback quality, there's this ridiculously tiny arrow to click for the dropdown selection that's almost impossible to hover over because it's so small. Why, exactly, did YT feel the need to cram all of the features into one button again?
But, they just came out with a new feature that's actually interesting for a change: whenever you're in your inbox, or your video manager, there's a new selection in the menu called "Community", which shows your subscribers' activity, based on how often they visit your channel, how often they watch your uploads, which of your subscribers are the most active, etc. It's actually kind of cool... so that means it probably won't last long.