The Latitude E6540 has a better storage medium than most medium processor core notebook PCs that are a comparable age to it. This notebook PC has an SSD storage medium, whereas most laptops of this age and spec have an HDD storage medium. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
This laptop's storage medium (SSD) is in fact the best storage medium across all medium processor core notebook PCs that were released around the same time as the Latitude E6540.
Across similar types of laptop the worst storage medium is HDD.