ahh, nope. not sure what you mean, with one of my plex machines (a little W10 NUC clone I literally installed W10, Chrome and Plex Player) no additional codecs and it has no issues, the PS4 client runs like complete arse all over the place and is laggy as fuck even when connected via a cable, XB1 not much better.
Where do you live? Antartica? Australia has access to all the Plex benefits, Jellyfin is missing a lot, eventually it will be good though. But it will always be missing a few things, for example never having a PS4/PS5 app, Sony won't allow it. Plex Pass gets you (And obviously not all are must have features) Mobile Sync Mobile App/Other Apps Premium Music Premium Photos Camera Upload Hardware Acceleration Bandwidth and Transcoding Limits Live TV Parental Controls Skip Intro (Great feature) PlexAmp (Great for playing music) Plex Dashboard Streaming Brain (Help manage bandwidth for your users) HDR to SDR Tone Mapping (A must for all HDR content you aren't direct playing) Basically, Sony controls what you can play, Microsoft Windows does not. This is why the PS4 will transcode things that its technically powerful enough to play, but its a lot better then it used to be based on my playback history for a friend who has one. In terms of actual app performance? Not sure, I've used the Xbox One app before and found it was great, besides me personally hating the new universal interface of Plex in general.
if you thought the XB1 app was good then good for you, the interface was too laggy for me even when connected via a cable.
What are you comparing it to? I found it about as good as other Plex Clients. Personally I use OpenPHT, which is basically instant/perfect and plays everything directly, but apps in general will never be that good (For some reason)