We measure the system USB 3.0 performance by using the excellent Patriot SuperSonic Magnum 256GB USB 3.0 drive, which we reviewed back in February this year.
No concerns with the USB 3.0 performance from the Gigabyte GA-Z87X-OC motherboard, hitting a sequential read rate of 276 MB/s. Write speed is slower, although this is limited to this particular drive, rather than the USB 3.0 controller. Due to the nature of this kind of flash, and via the USB 3.0 interface, 4k and 4k QD32 performance is substantially worse than from a native SSD drive across a SATA connector.
The ATTO Disk Benchmark performance measurement tool is compatible with Microsoft Windows. Measure your storage systems performance with various transfer sizes and test lengths for reads and writes. Several options are available to customize your performance measurement including queue depth, overlapped I/O and even a comparison mode with the option to run continuously. Use ATTO Disk Benchmark to test any manufacturers RAID controllers, storage controllers, host adapters, hard drives and SSD drives and notice that ATTO products will consistently provide the highest level of performance to your storage.
Performance via the ATTO disk benchmark is a little lower than in CrystalDiskMark, hitting a peak around 260 MB/s in the sequential read test and around 65Mb/s in the sequential write test. That said, these are excellent results for this particular drive.