These rough figures let you sanity check a design in seconds.
- L1 cache reference - about 1 ns
- Main memory reference - about 100 ns
- Read 1 MB sequentially from memory - about 250 us
- SSD random read - about 100 us
- Read 1 MB from SSD - about 1 ms
- Round trip within the same datacentre - about 0.5 ms
- Disk seek on spinning disk - about 10 ms
- Round trip between continents - about 150 ms
The headline: memory is roughly a hundred times faster than SSD, and a network hop across the world costs more than a thousand memory reads.