Interesting results.
mpv works fine, but I miss having a playlist and advanced controls (ie, speedup).
I discovered "smplayer", which gives a fuller feature set to mpv/mplayer, but it then has the same problems as I encountered with VLC.
As an alternative I had considered a high-end 42" 4K TV. They're about $600, and the lag time on high-end units should be acceptable for most uses except high-intensity gaming (which I don't do). The big difference in price is because TV manufacturers get subsidized for access to TV-watching data, which is a non-issue if the screen is not enabled for the Internet or "smart" features.