Very nice!
I love both the underlying focus on performance by the VTE developers, and the intense hardware-driven measurement process in the article!
The use of a light sensor to measure latency reminded me of Ben Heck's clearly named "Xbox One Controller Monitor" [1] product [1] which combines direct reading of game console controller button states with a light sensor to help game developers keep their latency down. It looks awesome, but it's also $900.