My Freenas box does not have CPU with AES-NI instructions. Freenas wizzard by default wants to add L2ARC with AES-XT 256 encryption, in my case that is huge performance downgrade. BUT! There is the workaround for that - add Cache device manually without encryption
gpart destroy -F "ada0"
gpart create -s gpt ada0
gpart add -l L2ARC -t freebsd-zfs -s 200G -a 4k -b 128 "ada0"
gpart list
zpool add DATA cache gptid/xxxxxxxxxxxxxxxxxxxxxxxxxxx...