Just buy the latest Apple TV 4K for a relatively low cost upgrade (compared to a new TV). I have a 2017 LG OLED model and I don’t notice any lagginess because I hardly ever use the TVs UI.I'ts really bad and extremely annoying. Even switching channels takes ages. I have the 2020 BX model and the UI also lags terribly. It's so bad, before I buy my next TV I will test the UI before and make sure it's snappy.