That's just one half of it: Intelligent defaults + configurability of what files/dirs to skip. That part has been iterated on in prior tools like `ack` and `ag

That's just one half of it: Intelligent defaults + configurability of what files/dirs to skip. That part has been iterated on in prior tools like `ack` and `ag` and `git grep` for like a decade, and ripgrep was informed by that tradition. The other part is extreme optimizations, from I/O and OS aspects to CPU, both asymptotic complexity (from scratch NFA regex engine), concrete complexity (rust, SIMD) and ad-hoc opitimizations for statistically common uses like fixed strings... Then there are some "product" choices driven by performance insights, e.g. no line numbering, defaulting to non-deterministic unsorted output order — these go against most programmers' intuition for "ideal tool I'd like", but turns out the speed gains are significant and what I really like is how fast it is :-) Both usability & optimizations are described in depth by the author in https://burntsushi.net/ripgrep/ https://burntsushi.net/ripgrep/, which is one of the best perf. readings ever, highly recommended.