In my experience, using spinning disks, the performance is very poor, and times for scrub and resilver are very long. For example, in a raidz1 with 4x8TB, scrubbing takes 2-3 weeks and resilvering takes almost 2 months. I must also add very poor performance in degraded state. This is a very old post, but things are still the same.

If op is considering ZFS: Do. Not. Use. RAIDz. (learned the hard way)