This is very very very wrong. GNU grep is not doing any optimizations based on "deep kernel knowledge" that ripgrep doesn't do. I'm honestly not even sure what you're referring to. GNU grep uses standard 'read' syscalls. ripgrep does that too (but also uses memory maps in some cases). There is some buffer size tuning, but otherwise, nothing particularly interesting there.

ripgrep's speed might come from ignoring files in any given use case, and it might even be the biggest reason why a search completes faster. But in my linked blog post, I control for all of that. Yes, while ripgrep might be faster in some cases because of its "smart" filtering, it's also faster in cases where "smart" filtering isn't enabled.