TESTED: 8TB OWC Thunderblade Thunderbolt 3 SSD
See also OWC ThunderBlade Gen 2: up to 8TB SSD, Runs Cooler and Faster at Lower Cost and Banishing the Drone of Spinning Hard Drives: and Fans: Moving to 8TB OWC Thunderblade SSD.
This is about as fast as a Thunderbolt 3 SSD can go (2.7 GB/sec). The speed is jaw-dropping across the entire 8TB of capacity for both reads and writes.
OWC Thunderblade Thunderbolt 3 SSD: Sustained Transfer Speed
Transfer speed across the various I/O sizes is similarly impressive:
OWC Thunderblade Thunderbolt 3 SSD: Speed vs Transfer Size