Another poster referred to this, but the most obvious reason for slow speed is intentional throttling due to thermal concerns.
It might actually have to be simply capped at an "always-safe" write speed due to limitations on the circuitry - is there room in an SD card format for adequate thermal sensors and the logic to limit write speed as the card heats up?
It might actually have to be simply capped at an "always-safe" write speed due to limitations on the circuitry - is there room in an SD card format for adequate thermal sensors and the logic to limit write speed as the card heats up?