2018 | 2017 MacBook Pro SSD Speed

2018

WRITE 2.6GB/S

READ 2.6GB/S

2018 MacBook Pro 1TB SSD

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2017

WRITE | 1.8 GB/s

READ | 2.3GB/s

2017 MacBook Pro 512GB SSD

Unless a glitch, transfer speed between the two devices in (one in Target Disk Mode) is kicked down to USB 3.0 (5Gb/s)