I think the playback issues, slow, stop, jump ahead, go fast..
Have more to do with your Video Card Drivers, than with anything else.
New software seems to keep track of the frame count, and if it falls behind, it skips some of the frames to catch up with the timing...
At least that has been my experience...
But as with any new release, it is as many have said, a work in progress and there are some kinks to work out..