DM365-USB transfer speed is slow.

hello, i had attach SSD hard disk (having ext3 partition) with my DM365.  I simply read raw data by directly open /dev/sdb with buffer size 512 byte. I get speed around 9-10 MBPS. 

when i attach same SSD hard disk with PC and read raw data then i get around 30-32 MBPS speed. Why reading speed is this much slow in DM365? Is there any way to increase speed at least up to 15-16 MBPS?

Thanks in advance.