I have seen a few threads on here asking about USB3 hubs and if they worked and, if so, which ones.
I didn’t see too many suggestions for working hubs, but I took the plunge and ordered one from Amazon UK and it works fine. I have 2 HDs plugged into it at the moment and can use Windows Explorer to copy/move files betweeen the 2 disks and the speed is as expected.
The hub is shown here:
Unitek 8-Port USB 3.0 Hub (USB 3.0 6-Port Hub + Two 5V 2.1A Charging Ports) With 12V 4A Power Adapter
http://www.amazon.co.uk/gp/product/B00DDF4YEM
Hope that helps.