On the home screen, you can watch the files actually being read through and where they are.
You can also see Counting on the status bar, which is basically a walk through source areas.
If you’re on Windows and running as an elevated admin, usn-policy can sometimes run faster.
Duplicati first identifies potentially changed files (e.g. timestamp changed), then reads those to
identify which blocks of the file actually changed and aren’t already in backup, then packages
those blocks into a series of temporary files which eventually get uploaded to your destination.
Typically when people worry about drive wear, it’s from SSD users worrying about write cycles.
If USN doesn’t fit, you can certainly split the backup as suggested using exclude as suggested.
Optionally, you can try to study where your time is going, monitor actual drive loads, and so on.