[forgotpwd16]

Replace `write(..)` with `puts("y")` and you'll be an order of magnitude faster. This is due to `puts` (`printf` too) being buffered (data isn't written to term/file immediately but retained in memory until some point). Improving this process (as seen in the reddit thread) gets GNU-yes.

[GoblinSlayer]

It's line buffered when it prints to terminal.

[jesprenj]

One rarely needs yes' output to be a terminal.

[throwawaymaths]

Don't you actively want it to flush asap since you're usually piping into another program?

I suspect what you suggest creates a more voluminous dump but is slower in the desired use case