[thrwwycbr]

"Up to xyz MB/s"

This very detail is the reason USB flash drives have useless performance numbers on them, which oftentimes lead to 1/100th of the advertised performance.

Everything that's bigger than the sector size (4k) is usually far lower than those numbers.

[wtallis]

Getting peak sequential read speed out of SSDs and USB flash drives usually requires issuing read commands that are much larger than 4kB, for two main reasons: the page size of the underlying flash memory is larger than 4kB, and SSDs and some USB flash drives stripe data access across multiple channels so you need to ask for at least a full strip of data. Queuing many commands for contiguous sequential reads can usually get close to the same performance, but has more overhead (and isn't an option for USB drives that don't support UASP).