[eregon]

Thanks for the comment.

> Cool, but what about replacing the regexp with straightforward parsing code written manually?

If you take a look at the linked snippets of C code, I think it's clear it's all but straightforward. The regexps OTOH are really short and expressive.

Ruby has no access to SIMD. And writing SIMD is basically writing inline assembly, so it's really tedious and messy.

> relying on the compiler doing autovectorization to make it fast.

I can relate to that, but Regexps are a much smaller domain, and there it's clear SIMD is always a win, so if the regexp engine uses SIMD it's very unlikely it would ever stop using it (unless something faster comes up).