[PatK]

I got smooth playback. That's an acceptable solution

Thanks for that tip, at least it usable.

mpv with VAAPI and the display set to 50Hz manually with xrandr. That played smoothly

Another great discovery would be using it as an external player within Kodi External players (wiki)

I'd like to find a fix for this.

Put something into the bug tracker and link this thread to it, but be patient there is a lot of irons in the fire atm.