Author here. When I was benchmarking my library against a ruby one, I did actually try the ruby one on 2.4. Interesting findings are:

- Switching from =~ to Regex.match? did not yield significant speed improvement

- Without any changes though, 2.4.0-preview1 ran the stemming in 19s, compared to the 25s on 2.3.1.

The ruby stemmer I used is this one: https://github.com/NeilNjae/porter2stemmer