Best-case for a SSD is more like 10µs, and the worst-case is still tens of milliseconds. Average case and 90th percentile are the kind of measures responsible for the most important improvements.<p>And the difference between a fast SSD and a slow SSD is pretty big: for the same workload a fast PCIe SSD can show an average latency of 208µs with 846µs standard deviation, while a low-end SATA drive shows average latency of 1782µs and standard deviation of 4155µs (both are recent consumer drives).