Alternative ways to run Plex?

Context; So... Just bought a brand new TV and life is good, but I should have done more research before buying it. I primarily want to use PLEX for watching media on the TV. However, due to "smart TV's" not being smart and being rather slow because most current TV operating systems are either bloated or just riddled with ads.

Question; So Plex is there, but it runs very poorly. What are the best options out there to get this running smoothly? Are the only options AppleTV and Amazon Firestick? Anyone been in this boat before that have any tips-n-tricks to share?

Ps. I hate ads, so the Firestick is of off the charts.

Much appreciated