The Apple Mac Pro Late 2013 has an SSD storage medium which is faster than most PCs of this spec and age. Most personal computers of this spec and age 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.
This personal computer's storage speed (SSD) is in fact the best storage speed amongst all PCs that came out around the same time as the Mac Pro Late 2013.
An HDD storage medium is the worst storage speed across similar types of personal computer.