I have connected my WD My Pasport to a 3.0 usb port and a 2.0 usp port. The 3.0 would only give me transfer rates between 400Kbs to 700Kbs. The 2.0 gave me transfer rates between 9Mbs to 21Mbs. Why is the 3.0 so much slower when it is stated that the transfer rates could be as high as 4 Gbs?
Make sure you are properly differentiating USB 3.0 from the 2.0 ports.
The transfer speed will also differ when you are copying small files versus big files.