Help with improving Jellyfin performance

[TheDreadPirate]

You'd have to look at the logs to verify that it is the subtitles that is triggering the transcode. There is a field called "TranscodeReason". Regardless, tone mapping is the killer here. The N3350 is an older 6w CPU. It just doesn't have the horse power to handle HDR tone mapping. I had a J4205 running my Jellyfin for a while, same family but higher performance, and it barely handled 1 tone mapped stream.

Regarding playing the video via the built in player vs Jellyfin on WebOS, they are likely using different underlying players. The Jellyfin WebOS app is dependent on WebOS's browser player, IIRC. ASS subtitle support is inconsistent. As is HDR support.