One drawback of the release notices is the update after major release is partial.
Here’s what changed for all of the 2.2 Stable releases. One has to go digging…
Blog post: Cut restore times by 3.8x - A deep dive into our new restore flow
FWIW I saw almost no improvement on my old system. Forum has quite a few complaints about the management of temporary files within new cache design.
Restore methods speed comparison describes some improvements underway.
I don’t know if there are any useful stats kept by Duplicati to identify disk usage.
Windows users can watch the process with Sysinternals Process Monitor to see what sort of operations are hitting the drive. Database would probably be either database pathname or some suffixed version of it. SQL temporaries are etilqs.
Restored file paths should be obvious. Temporary files such as cache for restore probably begin with a dup- prefix, but really this is an area for developer assists.