Well, Ubuntu 23.04 is here and it's time for the new round of ZFS encryption testing. New version, minor ZFS updates, and slightly confusing numbers at some points.
First, Ubuntu 23.04 brings us to ZFS 2.1.9 on kernel 6.2. It's a minot change on ZFS version (up from 2.1.5 in Ubuntu 22.10) but kernel bump is more than what we had in a while (was kernel 5.19).
Good news is that almost nothing has changed as compared to 22.10. Numbers are close enough to what they were before that they might be a statistical error when it comes to either AES-GCM or AES-XTS (on LUKS). If that's what you're using (and you should), you can stop here.
Every few reads speed would simply start dropping. After a few slower measurements, it would come back where it was. I repeated it multiple times and it was always reads that started dropping while writes would stay stable.
While that might not be reason not to upgrade if you're using AES-CCM, you might want to perform a few tests of your own. Mind you, you should be switching to AES-GCM anyhow.
As always, raw data I gathered during my tests is available.