I have been trying to figure out why since I started using it... searches spin forever, videos spin forever, some videos just spit "Error 1003" immediately, and then they become accessible 10 minutes later. I even tried filing an issue to no avail. I may end up looking for other alternatives.
I have, but the ones I tried weren't much better. I looked again and there's a few new ones, so I'll try those and update if they work faster/more consistently.
That's why I've been using YouTube without logging in and if using in browser, I have the cookies autodelete after I close the page to start new each time.
It never really recommended me what I wanted anyway. I guess the algorithm doesn't work on me.