Text:
I consent to Plex to: (i) sell certain personal information (hashed emails, advertising identifiers) to third-parties for advertising and marketing purposes; and (ii) store and/or access certain personal information (advertising identifiers, IP address, content being watched) on my device(s) and share that information with Plex’s advertising partners. This data is used to deliver personalised ads and content, ad and content measurement, audience insights and product development. Your consent applies to all devices on which you have Plex installed. You can withdraw your consent at any time in Account Settings or using this page.
Soure: https://www.plex.tv/vendors/ (Might have to clear cache)
Can also read about the changes here: https://www.plex.tv/about/privacy-legal/
Plex is heavier, of course. They don't have the spending luxuries that Netflix or Disney has to optimize for every platform perfectly. That said, TV's notoriously use inferior hardware for the built in streaming portion so they can sell them at the prices they do and make higher profit. Sure, they can play the media they were designed to do, but that is the bare minimum requirement. They also sell your data to recoup more profit.
Unlike good dedicated streaming devices, they lack the processing power needed to make it go quickly. I have both and it is a night and day difference in responsiveness in the UI. It either lacks the memory/CPU power to work as well. Don't just take my word for it though, do your own testing or look at somebody elses. Plex definitely has improvements that can be made, but they are not at complete fault here.
If you pick a good dedicated one, it might not even sell you out to advertisers. Lol. You don't really want to connect your TV to the internet anyway. They phone home constantly.
This all still doesn't address the first thing I wrote:
Why can Jellyfin perform perfectly on the same hardware? Very snappy. It's obviously not the hardware's fault, but more a lack of optimization — and testing. If they tested/dogfed their app on WebOS at all, they'd know it's ass.
Edit: I just did a quick research on this in the Plex forums, and it seems like a lot of posts detail the same experience as mine: Plex used to work great until a year or more ago where it just turned into an unoptimized mess where even stepping left or right to a different poster, or button, has like a 1+ second lag.
It's very clear this is Plex's fault. It wasn't always like this.