I've been surprised with the lastest speed test done on my IMAC 5k late 2015 1Tb Fusion Drive (24gb) done a Blackmagic (version 3.0). I used to get around 350 Mb/s write and 850 Mb/read, but setting the target to icloud drive and stress of 1Gb I've got up to 1550 Mb/read and 330 Mb/write. Does anyone knows why does this happen? Does anyone gets similar results? I Have a Mac OS Sierra installed.