The Lenovo Flex has an HDD storage medium which is better than most 2 in 1 laptops that are a similar age to it. Most 2 in 1 laptops that have been available for around the same time as 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.
This laptop's storage medium (HDD) is in fact the worst storage medium amongst all notebook PCs of a comparable age and type to the Flex.
An SSD storage medium is the best storage medium amongst similar types of laptop.
If you are looking for a notebook PC with a better storage medium then you might also want to consider the Lenovo Yoga (SSD), or the HP Pavilion x360 (£382.66) (SSD).