I didn't realize it was updating all the opfs ... didn't actually think about it ...
but that should still be much faster than the unpack/count process, shouldn't it?
And doesn't Extract ISBN do the same thing? I've run that against entire libraries and the update process was a small fraction of the extract time.
I kinda expected similar runtimes to Extract ISBN, and from what you just said, kiwidude, the update processes are indeed the same (except that the last time I ran a bulk Extract ISBN was with an earlier version of Calibre).
I don't think it's an anti-virus issue. The libraries are excluded, as are the calibre and calibre-parallel processes. And the temp folder isn't excluded, so any AV delay should mostly impact the unpack/count process not the opf update ...
I'll try again when I can free up the computer, start from a clean boot, etc.