Hellou,
After update PVE to version 8.4.11 (Before PVE 7.4) and PBS 4.0 (Before 3.4) backup CTs is very slow. In version 7.4 this time backup +/- 30 minutes, after update this backup time is +/- 1h15. Attachment actual configuration backup.
I investigated all configuration, RAID, network, CPUs...