TrueNAS 12U1 less than half the read speed of FreeeNAS 11.3U5?

So I have been hesitant to upgrade my trusty FreeNAS machine to TrueNAS 12, even though it would bring a couple of features I'd like (most notably native encryption and encrypted replication). I thought I would check it out on a spare machine and also run some tests and benchmarks with the encryption...

The system I used is a Dell Poweredge R420, with a single E5-2403 CPU, 48G RAM and 4 2TB SATA 5400rpm drives.

I never got around to running tests with encryption, because no matter what I...

TrueNAS 12U1 less than half the read speed of FreeeNAS 11.3U5?