"The CPU," he said, "runs at a certain speed. It can execute a fixed number of instructions per second, and no more. There is a finite limit to how many instructions per second it can execute. Right?"
"Right," I said.
"So there is no way, really, to make code go faster, because there is no way to make instructions execute faster. There is only such a thing as making the machine do less."
He paused for emphasis.
"To go fast," he said slowly, "do less."