I don't think the speed is the issue here. My guess is framecuts. I didn't really invest much time yet, but I will have more time next weekend, if there is still something wrong. I'm normally a perfectionist, but my time was limited and it also was the first time I did this (syncing LD audio to Blu-ray video).

About time stretching: Can you elaborate on the downsides to that? Especially when its just used filling a 20 ms gap.

I was also thinking about the analog capture ilovewaterslides made. I have absolutely no experiences with Laserdiscs. If a Laserdisc features an analog and digital audio track, are they always from the same master? Could it be that the analog track is superior to the digital one, because less compression was applied (similar to vinyl captures that offer a higher dynamic range than Audio-CDs)?