[johntash]

Borg sequentially scans your filesystem for changes and only then starts backing up changed data. (tbf: a lot of backup tools seem to do this)

Restic scans your filesystem for changes, and then also starts backing up the changes it finds in parallel while it is still scanning for more changes.

When you have millions of files, this makes a huge difference.

[formerly_proven]

This is wrong. The difference between the two is that Restic uses multi-threading and Borg currently doesn't. Both just scan the filesystem and add files to the backup set as they go.

[johntash]

Hmm, maybe it has changed or I'm remembering wrong. It's been years since I tried borg, but I remember it taking something like 10 hours to scan for changes, and then another 4 hours or so to actually backup the data.

With restic, it still took around 10 hours to scan for changes, but it was also already done backing up all the data by the time the scan finished.