I think the problem has been solved in 1.1.0 alpha version. Already tested a few HD films and everything works fine.
Maybe because of that: 0002070: [Skin Engine] EVR renderer doesn't provide fps information (Tourettes)) - closed.
I'm pretty sure that it doesn't fix the issue, as it just providing the fps to the user for debugging...
It was just a speculation.
The fact is that still it works (till now). I moved forward & backward many times in HD movies and no lip sync problem occurred.
What about after playing a video for 15mins, is lip sync OK after that time?