What is your hardware ?
Which NIC do you use?
The best NICs for FreeNAS are
- 10G: Chelsio or Intel.
- 1G: Intel
We have 1GbE, 10GbE (SFP+ and 10Gbase-T) and 40GbE networking options for the top FreeNAS NICs as storage performance is network dependent.
www.servethehome.com
Nevertheless, there are other NICs that work very well, like the Broadcom BCM5720 which is found on many HPE and DELL servers.
I have a HPE Proliant Microserver Gen8, with a Broadcom BCM5720 1G NIC on board, and it works very well.