The Mac Pro Late 2013 has a faster storage speed than most medium processor core PCs that were released around the same time as it. This desktop computer has an SSD storage medium, whereas most medium processor core PCs that came out around the same time as it have an HDD storage medium. Solid State Drives (SSD) store information in transistors on a circuit board rather than on optical or magnetic media. This has the advantage of being much faster than a traditional HDD drive.
An SSD storage medium is in fact the best storage speed amongst all computers of this age and type.
The worst storage speed amongst similar types of computer is HDD.