Hello, my issue is first faced on FreeNAS-11.2-RELEASE-U1, but it can be reproduced on plain FreeBSD 11.2, and 12.0 (even worse). Also posted on FreeNAS forum, but no replies there.
So here is my setup:
Here is my specs:
Dell T310 (Intel(R) Xeon(R) CPU X3470 @ 2.93GHz, 8GB RAM)