The Asus Chromebox M064U has a faster storage speed than most personal computers of a comparable type and age to it. This computer has an SSD storage medium, whereas most few 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 actually the best storage speed amongst all few processor core PCs that were launched more than a year ago.
Amongst similar types of computer the worst storage speed is HDD.
If the storage speed of this personal computer is too slow for you then you might also want to consider the Apple Mac Mini Late 2014 (£659.47) (Flash).