The article is about testing actual user experienced latency, and Mutter still buffers 1 frame. Actual observed latency is going to be between 16.6ms and 33.3ms

The article is about testing actual user experienced latency, and Mutter still buffers 1 frame. Actual observed latency is going to be between 16.6ms and 33.3ms before the user can see anything hit their eyeballs.