SanDisk Extreme USB 3.0 64GB Flash Drive - slow performance

Device tree says:

[…]

        ---------------- Connection Information ---------------
Connection Index         : 0x02
Connection Status        : 0x01 (DeviceConnected)
Current Config Value     : 0x01
Device Address           : 0x01
Is Hub                   : 0x00 (no)
Number Of Open Pipes     : 0x02 (2)
Device Bus Speed         : 0x03 (SuperSpeed)

[…]

…and yes: I did suspend anti-virus/security during my performance tests