USB flash drives are mostly just as bad. Many advertise large read/write numbers but they overwhelmingly all hit a wall once the MB or two of cache is full. And

USB flash drives are mostly just as bad. Many advertise large read/write numbers but they overwhelmingly all hit a wall once the MB or two of cache is full. And they seem to be as unreliable as SD these days. The solution is USB->SATA SSD converters with SATA SSDs. Those will easily sustain a few hundred MB/sec read/write. The problem then becomes the USB inefficiencies, but for the most part wear leveling/etc make them pretty bullet proof. The PFTF UEFI firmware will reliably boot off just about everything you can plug in (USB DVD/etc included).