My desktop only had USB 2.0 ports - until yesterday, when I installed a RocketU 1144D controller card (4 ports). Put it through its paces by making a 400+GB image of my C drive to an external USB 3.0 hard drive. From start to finish it took an hour and 4 minutes.
Don't know if I set any speed records, but compared to the last image I made via 2.0, this was blazingly fast.