@waylow Yesterday it worked with the settings I’ve mentioned above:
1) “Playback” in the “Timeline Editor” set to “Sync to Audio”
2) “Caching” box for the “Audio Strip” in the “Video Sequence Editor” checked
3) Closing some background applications.
Today, it unfortunately didn’t work again despite the same settings and closing even more background applications. It seems to me to be a game of luck whether the scrubbing playback has a sufficient quality or not. That’s very frustrating 😪.