Interesting project, writing a useful PHP extension is an every web developer's dream.
However, the licence choice is weird. It's really asking to be MIT. Any company bigger than 2 people pays attention to that. Most web projects are proprietary. GPL‑v3-or-later is not appropriate for proprietary/closed-source.
Also, the README is lacking a nicely looking comparison chart, motivating people why they should use your project instead of just running grep in shell_exec. I'm very unlikely to run the benchmarking scripts myself. You have to convince me why your project is better than the established industry practice.
> GPL‑v3-or-later is not appropriate for proprietary/closed-source.
Perhaps that's the intent of the author. Not everyone is a fan of allowing companies to use your project for their closed source, proprietary garbage.
It's refreshing to see a project that isn't MIT.
The plugin directly adapts code from GNU Grep, so they MUST release it under the GPL, as far as I understand.