The Slot-in PC has an SSD storage medium which is faster than most similar spec PCs that have been on the market for around the same time as it. Most few processor core computers that were released more than two years ago 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 actually the best storage speed amongst all desktop computers of this spec and age.
Amongst similar types of computer the worst storage speed is HDD.