Seems like when subtitles are being shown on screen the video it running at a lower framerate, which makes the video a little jerky. Running smoothly when the subs are gone.
Can you try updating to Beta7 to see if things improve?
problem remained with 7.1 player. But could be related to the DVD-source, will download another to try.
Just tried another DVD, had no issues, so it’s probably just this one DVD causing the issue.