EDIT: MimeticM beat me too it. Thanks for the great info!
Some musings for fellow external-folder-sync travelers:
I found this in the forums: 2.7 syncing much slower than 2.6 - #2 by AmberV
This may be what I’m encountering – spooling through all the documents in the entire scrivener project file before syncing just the ones it should target.
Luckily I’m no longer experiencing the slow-downs after I reset the sync and restarted the computer/Scrivener. Hopefully the quick sync continues. As for the number labeling, it may be a function of combing through all the files, regardless of the small subset that I’m actually syncing.