File transfer rates is a common complaint with not only the My Cloud but with other NAS devices. There are a number of factors that can affect transfer speeds. First thing to understand is that the rates advertised (1 Gigabit, etc.) are just that, advertised speeds. It doesn’t mean you’ll ever obtain that speed when transferring data. Usually there is very fine print on the box that say something like; “up to” the advertised speed. Second, there are limits introduced due to the hardware used on the NAS drive itself that can cause lower than expected data transfer speeds.
If you haven’t already done so read through the following thread that talks about data transfer speeds and factors that can affect it: