Speed up disk cloning over USB
Disable Spotlight

Spotlight is Apple’s technology for indexing all your disk’s contents to facilitate fast searching. 

When making a disk clone, you do not want the booted Mac to re-index all that copied content. No need. Worse, Spotlight is fighting for the limited USB to read from that external disk while SuperDuper is trying to write to that external disk. 

Fortunately Apple provides a "Privacy" feature where you can pick a folder, or even an entire disk, telling Spotlight to ignore the nested content. In System Preferences app, in the Spotlight option, click the Privacy tab. There you can add your external disk to the list of exclusions. Click the plus-icon button and select the external disk.

This sped up my disk-cloning multiple time faster, at least 3-5 times faster. At first, after 10-20 minutes, it looked like 233 gigs would take 24-30 hours to clone. Then I used Spotlight > Privacy. Over 10-20 more minutes, the throughput reported a doubling of speed. Cloning took 4 hours.



Remove Drive

…try at your own risk…

Another option is removing the hard disk from inside the MacBook. Then use Voyager-type or such to attach to another Mac with FireWire/Thunderbolt ports to do the copy. 

Removal is easy enough to do if you have a model with a removable battery. The disk is accessible through the battery bay. 

The only trick is sometimes the rubber strip that hold the drive in place. If that comes loose while sliding the drive back in, things get tricky.