Crashplan backup to USB 3 drive is slow

[Phastor]

Got all my data transferred over to the new server and running my first backup. It's targetting a USB3 drive. Right now it's reporting to run at around 100Mbps, so roughly 10-12 MB/s. That seems to be a bit on the slow side.

I'm using a PCIe 1x USB 3 card since the motherboard I use doesn't have it. While the PCIe 1x bottlenecks USB3 throughput, it still should be plenty to max out a spinner. My guess is that unRAID either doesn't support 3.0, or it's just not recognizing the drive as such.

I know that Crashplan does compression, and because of that I wasn't expecting 100 MB/s speeds. Though I wouldn't expect it to drop transfer rates this low.

Any ideas?