I was getting slow speeds 8MB/sec on decent hardware. Heres what I changed
Under Sysctls, add net.inet.tcp.delayed_ack 0
under CIFS Settings enable the following
Large RW support
Send files with sendfile(2)
EA Support
Enabile AIO
Min/Max AIO read/write Size 4,096
I'm now pushing 80-140MB/sec on my box.
With that said get more ram.