I got two free AppleTV 4K’s by taking advantage of a promotion from DirectTv Now, the difference in performance between them - with an Apple A10x chip - and the built in Roku TV is noticeable.
But if you have a smart TV that’s not a Roku, it’s probably even worse.
Also I bought a very expensive TV, and while I didn't dissect it I don't think there are any cheap parts in it - and the reviews all agree it had a top-of-the-line processor at the time and that was only a year ago. I mean it even has glass bezels for the OLED panel.
I don't think anything you say applies to my situation at all. I think Hulu just has some shitty software.
I'm glad it works for you, but it's pretty awful for me.
Does Hulu work on your normal computers (e.g. not a network-related issue)? Everything updated?
I don't know if this works or not, but you might want to try and plug it into a Mac and launch Console to get a sense of what's going on....