Originally posted by angerdan Since the SD slots are connected just to USB 2.0,
What leads you to this curious assumption? Are you talking about the camera's connection to a PC, thus using the camera as a card reader?
That's completely unrelated to the way the camera itself accesses the SD cards.
And, no, neither of the SD-card slots is an UHS-II slot. The slots are different, number 1 has two "double contact" springs instead of only single contact spring as numer 2, but this is a mere manufacturing difference, due to the different mechanical properties of the slots. Both might be mounted on the same PCB (printed circuit board), one lying flat on it's surface, the other one with long standoffs and longer "pins".
That's all.
Besides, the camera's write speed (which is limited by the speed the sensor can be read) is much lower than what a decent UHS-1 SD card can deliver.
That the sensor's the "bottleneck" here can be seen when comparing the frame rate achievable with a Nikon D810, which uses the same sensor.