The Mac Pro Late 2013 has an SSD storage medium which is faster than most computers of this age and type. Most medium processor core PCs that have been available for 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 across all medium processor core PCs that came out more than a year ago.
An HDD storage medium is the worst storage speed amongst similar types of personal computer.