WebOS Struggles w/ DS4K+HDR Content

[Host-in-the-Shell]

Do you by any chance agreed to everything under the terms of service for the TV? I had terrible performance issues on the JF app, manifesting itself similar to what you describe, until I deselected everything under the terms agreements and only kept the required terms. Turns out selecting all of that stuff makes your TV eat through a lot of memory and is specially noticeable during 4K HDR Playback in which audio is being transcoded or if you are using complex ASS subtitles, at least that was my experience.

You may also want to unplug the TV for around 5 mins to clear out some memory just in case.