Hi,
I have a rather large torrent going (2.8 TB) that's updated every month by adding/replacing a couple of GBs only. When adding the torrent at first, the verfiication process took about 6 hours. Now (since probably a year or so) it takes a week (or even longer, as I deleted it before completion while the remaining time indicated kept getting longer).
The torrent content is located on an external Thunderbolt disk (if it makes any difference) and I'm using the latest nightly build on macOS (also latest version).
Why has the verification process got so slow?