I used my WD Passport Ultra for MAC (5 TB) to do a full back up of my MacBook Pro. It backed up 90 GB out of 280 GB in 12 hours. I quit the backup and used my WD Elements (10 TB) drive to do the same thing. It completed the backup in 3.5 hours. So the WD Elements is more than 10 times faster at backup than the WD Passport Ultra! I used the same backup program (TimeMachine) and did not restart the MacBook Pro between backups. I used the original WD cable on the Passport Ultra and also an Anker cable. The speed with both was slow. Is the drive bad or could something else be going on?
Please refer to this KB article as the drive performing slower than expected: Benchmarking programs indicate that my hard drive is performing slower than expected
Regarding the KB article, I did not use any benchmarking programs, I just compared the Passport Ultra and a WD Elements drive. The Passport Ultra for Mac showed no problems with Disk Utility and I was performing the backup comparisons with the Passport Ultra empty.
I also tried two different data cables on the Passport Ultra, which did not change the outcome. Since then I have compared the two hard disks in copying two large folders on an iMac with similar results: the Passport Ultra was 5 times slower than the Elements.