You plugged a USB2.0 flash drive into a USB1.1 port. It's the last thing you want to do if you want decent performance. USB 2.0 can theoretically reach a throughput of 60MB/s, although you normally won't see more than 30MB/s even with a good flash drive. USB 1.1 is theoretically limited to 1.5MB/s, but you'll often get less.