@jasoncox If the USB-C (charging) cable that came with the iPhone is used, USB2 speeds are to be expected. With a Thunderbolt cable, USB3 speeds can be attained during the migration’s data transfer. @BasicAppleGuy
@BasicAppleGuy does this transfer actually copy all of the keychain so that you don't need to enter usernames/passwords? I have always plugged into a Mac and made an "encrypted backup" then restored to the new device.