Two backups were just run together, one a SuperDuper! clone, the other a Time Machine backup. The former was via USB 2.0 & the latter over FireWire 800. I do a fiddle with Terminal to take Time Machine from a background operation & make it a high-priority one instead.
The Time Machine backup of 7.5 GB finished 5 minutes before the 6 GB clone, despite the clone having started a minute before the Time Machine drive was connected.
This MB Pro can only have USB 3.0 when a dock or an adaptor is attached via Thunderbolt & the T/bolt connection is currently used for the 20-inch monitor.