3 GB/s is impressive, but I’m more curious to hear about the application that gives a Y/n prompt 1,500,000,000 times per second.
yes is useful for more than just interfaces: it’s effectively a more flexible /dev/zero.
Optimizing it is obviously golf, but on the other hand, it’s unlikely to hurt anything.
There are plenty of applications that write loads of data through pipes, so while this example is kind of useless in of itself, it does provide a good platform to experiment with pipe perf. The Reddit discussion linked even has some good discussion about kernel internals.