SUMMARY I have a normal modern laptop (AMD 7840) and a modest amount of data (~1TB). When creating a first backup on a clean fast SSD drive generating recovery information is now taking hours. Then on subsequent backups verifying the previous backups again takes hours. Kup seems to be limited to 4 threads, whereas my laptop advertises 12 cores. IO top tells me that the max read/write speed is in the 10s of MBs whereas the drive supports 100s. For now I am forced to disable these extra protections, so that I can be sure that the backup will complete in a reasonable amount of time. I'd love to see kup go faster.
Just wanted to chime in to say, yes, generating the initial recovery information is very time consuming, but it makes sense. That said, for me on a similar system, generating the recovery information on subsequent backups is rather quick and I assume this is because bup is only generating this for the new data that was backed up. While it might makes sense to dedicate more cores to this, assuming it's possible, you'll also want to find the balance here to keep your machine performant while the backups are running.