WD Passport 1TB USB 3 - Very slow for USB 3... even after Format!

Yep. I totally agree. But a faulty disk surface can be remapped by the error checking built into the drive. This happens without you knowing it. This covers hardware faults and soft faults equally.

Sometimes this routine gets stuck in a loop from time to time. Especially with software errors and power loss conditions. And the best way out is to zero and format the disk with the non-quick windows format.

You can try chkdsk and scan and recover bad sectors. This won’t work like HDD Regen or SpinRite, but it might trigger the disk’s internal routines differently and force a remap.

You can find a secure erase utility which would do something similar. It basically triggers a secure erase to be done by the disk’s firmware and in the process of overwriting each and every bit it would write several reversals as a matter of course. All new disks have this capability. You may need to connect the disk directly to the computer, because USB bridge controllers don’t pass all commands to the drive. – http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtml

If that doesn’t work the next choices are HDD Regenerator or SpinRite.

 I’ve used HDD Regen and SpinRite several times to fix disks that failed in brownout conditions. The servo markings are never touched, but the weak sector marks were refreshed just fine.