So I'm currently running Mint 17.1, but this happens with all the distros I've tried. When transferring a file to a USB stick, external hard drive, other internal disks, and even the FreeNAS server, the file transfers start off nice and fast then gradually slow until they flatten out, usually at less than half the speed. For example, I might end up with 40MB/s on an internal hard drive. Unless this can be solved, I will be switching back to Windows.