The Lenovo Flex has an HDD storage medium which is better than most portable PCs of this age and spec. Most portable PCs of a similar type and age to it have an SSD storage medium. HDD is a traditional storage drive which stores the information on magnetic disks. HDD drives are slower than other forms of storage such as solid state drives (SSD) and flash drives.
An HDD storage medium is in fact the worst storage medium amongst all laptops of a similar spec and age to the Flex.
An SSD storage medium is the best storage medium amongst similar types of portable PC.
Notebook PCs with a better storage medium that might also be worth considering include the HP 13-r100dx (£1,054.30) (Hybrid-HDD).