Here is my super dumb implementation. Doesn't handle multibyte, doesn't handle stdin -- but I don't think the Haskell version did either, so I don't have a problem with that limit.

https://github.com/ojhunt/wc

It's the simplest thing that could obviously work, but its generally not tested beyond the most basic versions.

I’m comparing to Mac wc, which is apparently what they were testing against, and I was getting twice that perf without anything clever.

That said I’ll try to post my horrifying impl to GitHub later :)