RAIDZ reads are slower than writes

Hi there,

I installed freenas a few days ago.

My hardware is as follow:
- HP Microserver gen 8
- upgraded CPU Intel Xeon E3-1265L V2
- 16 GB of ECC UDIMM
- 4 x 4TB seagate NAS HDD ST4000VN000
- Single RAIDZ1 pool

I have a major issue with ZFS speeds. Reads are slower than writes. I was hoping to have at least read speed = write speed....

Writes speed is ~100MB/sec:
[root@freenas] /mnt/volume1/documents# /usr/bin/time -h dd if=/dev/zero of=sometestfile bs=1024 count=300k
307200+0...

RAIDZ reads are slower than writes