Your comment brings ripgrep to mind. Grep is about as ubiquitous a software tool as you can get with a very clear contract on input-output and it has absolutely stood the test of time. Then ripgrep comes along, it has the same contract as grep (with I think a few inconsistencies that were intentionally tweaked for modern use-cases...and also I'm sure a few edge-cases from its design), but is significantly faster. The fundamental contract with the user stayed the same, I'm sure some of the design changed, but fundamentally the only difference is the underlying code. And that makes such a big difference that I *always* use ripgrep over grep now as do many others.