Backing up to a NAS currently says 3 days (!) left, after having backed up ~160GB. Was using WiFi with TX rate 133MBit.

Now I connected using Gigabit Ethernet, does not seem to be faster.

Plus: CPU usage is ridiculously high, fans spinning up to medium/max speed several times per hour.

[...]

I did not change all files on my disk ...

Maybe they removed the alert that was shown when the backup got corrupted? Seems to be the case because I did not get that alert and all my old backups (on the NAS) seem to be gone.

[...]

So it seems like Apple indeed removed the confirmation dialog that they showed when they delete corrupted backups, taking away the chance to manually repair it.

I wonder whether this happened pre-Sequoia? Even on Sonoma, I would regularly have Time Machine backups where I would imagine that less than 50 GB changed, but it took all day to back up to a local hard drive. (Yet it wasn't so slow that it seemed to be starting from scratch.) I wish Time Machine were better at showing which files are being copied and how the space is being used. (I guess some of this can be figured out using BackupLoupe.)

Miguel Arroz: