On older but good 2.0 m long USB2.0 cable that was plugged into the 3.0 port, the same USB3 sticks (Verbatim, SanDisk and Winten) were quick:
well over 20 MB / sec while reading and 14-17 MB / sec while writing
Conclusion: the cable brings an improvement and it is always used as the front USB ports are slower on the housing.
More speed but would be very pretty. Perhaps a reader has a good tip!?!
I wanted to join a USB3 hard drive from WD. This was not recognized by the PC via this cable.