I'm getting ~3.10GiB/s with both GNU's and FreeBSD's. I do see that GNU's version has some optimizations, but their effectiveness isn't apparent when doing `yes | pv > /dev/null`.

However, my point was just that its performance was never a main point of it. Even without optimizations, it's still very fast, and I don't think whoever created it first was concerned with it having to be super fast, as long as it was faster than the prompts of whatever was downstream in the pipe.