[pron]

To understand what happens when the server doesn't perform IO, apply Little's formula to the CPU only. Clearly, the maximum concurrency would be equal to the number of cores, which means that in that situation there would be no benefit to more threads than cores. What you would see in the graph would be that the server fails once L is equal to the number of cores. The average ratio between IO and CPU time as portions of the average duration would give you an upper limit on how much more throughput you gain by having more threads. That's what I explain at 11:34.

Also, both throughput and latency are performance metrics.