Doing science is great, but first we need to make sure we're not comparing apples and oranges.
OP has defined the problem as speeding up an HTTP server (libreactor based) on Linux. So that's a context we assume as a base, questions like "what can the hardware do without libreactor and without Linux" are not posed here.
If your problem is "speeding up X", one of, if not the first question you should ask is: "how fast can X be"?
If you don't know, find out, because maybe X is already as fast as it can be, and there is nothing to speed up.
Sure, the OP just looks around and sees that others are faster, and they want to be as fast as they are.
That's one way to go. But if all others are only 1% as fast as _they should be_, then...
- either you have fundamentally misunderstood the problem and the answer to "how fast can X be?" (maybe its not as fast as you thought for reasons worth learning)
- what everyone else is doing is not the right way to make X as fast as X can be
The value in having a model of your problem is not the model, but rather what you can learn from it.
You can optimize "what an application does", but if what it does is the wrong thing to do, that's not going to get you close to what the performance of that application should be.
OP has defined the problem as speeding up an HTTP server (libreactor based) on Linux. So that's a context we assume as a base, questions like "what can the hardware do without libreactor and without Linux" are not posed here.