As someone familiar with JS engine regex internals, those results are totally shocking to me. How can I try your example? In particular I wasn't able to figure out which regexes you are testing with.
/^abcd(a(b|c)*d)*a(bc)*d$/
It's possible I made a mistake somewhere, and I can put together an open-source repo with the test setup when I get the time. But I'm curious why you find the results shocking?
One thing I spotted is that you're asking the native engines to record capture groups, but your wasm implementation doesn't support those. For fairness you might switch to non-capturing groups: `(?:bc)` instead of `(bc)`. However this cannot explain the magnitude of the difference.
I dug into it some more, reducing it to this case:
/^(?:abc*d)*$/
Regardless it's a cool project, thanks for sharing!