A version of Yes, an app that says "y" at maximum speed, is built-in to unix-based operating systems. You can test it by firing up a terminal, typing "yes", and then watching it fill your window; you'd usually pipe it to another app or script. But there's a problem: it can only generate 51 megabits per second worth of yes, and something must be done about it.
The trivial program yes turns out not to be so trivial after all. It uses output buffering and memory alignment to improve performance. Re-implementing Unix tools is fun and makes me appreciate the nifty tricks, which make our computers fast.
As benchmarked by the author's computer, 3GB/s of yes is now possible!