Speed up OS install USB creation by using unbuffered I/O on macOS

You can speed up install USBs dramatically by using /dev/rdiskN instead of /dev/diskN, e.g.:

sudo dd if=/path/to/iso of=/dev/rdisk2 bs="1024"

Don’t forget to eject the drive:

sudo diskutil eject /dev/disk2

A detailed explanation on the rdisk performance can be found on Superuser.