The NEC Slot-In PC has an SSD storage medium which is faster than most desktop computers of this age and spec. Most desktop computers of this type 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.
An SSD storage medium is in fact the best storage speed across all desktop computers of this age and spec.
The worst storage speed amongst comparable types of computer is HDD.