It would be interesting to see the results of this simple experiment for different web frameworks: almost empty template and no other processing => how many requests per second? If it's much slower than i/o times, something should probably be done about it.
This would be much better experiment. Who does web apps on bare languages anymore? And any decent framework will have some caching implemented, so you don't render the same template if nothing changes.
(BTW I completely agree with antirez's point.)