I recently bought a Sandisk Extreme Pro 128GB USB 3.0 Flash Drive that states "up to 260MB/s Read and 240MB/s Write speed". The board has the latest Intel and Asmedia USB 3.0 host controller drivers for Windows 7 64-bit. Not running AI Suite or USB 3.0 Boost (should be?). BIOS is 1903.
Last night I copied several folders of images files (mostly JPEG) totaling 105GB from Crucial m4 SSD to the SanDisk Flash Drive and saw sustained 120MB/s which by all account is fast but just isn't fast enough. I have seen several reviews where people got very close to the advertised speeds for both reads and writes including an AnandTech review saying theirs was just 50MB/s short. Mine's half that and I was wondering if there's any hope of increasing the throughput at all. I have also read the many of Asus gaming boards suffer similar USB 3.0 related speed issues.
FWIW, I have also tried changing Removal Policy from Quick Removal to "Better Performance" and instantly saw a drop in transfer speeds (the irony). It would burst at 260MB/s and you can see speed quickly deteriorate to 50MB/s. Weird.