Just bought an Extreme USB 3.0 Flash Drive 64GB and copied some 3.6 GB from my Win7 PC using a USB 3.0 slot.
Felt somewhat slow, so I used H2testw to get an “independent” oppinion:
Write speed: 59 MB/s
Read speed: 72 MB/s
After 6 GB the dongle disconnected an Win aksed me to fix the drive.
Somewhat disappoining for a stick that comes at double the price of a std. USB3 stick.