Yup, this article is an oldie, but also a goodie, and I like seeing it reposted because it shows a terrific programmer speaking about their work with great passion, and it reminds me how to carefully answer questions without a condenscending tone (be that tone accidental or not, it's very easy to be off-putting when you are "idolized").
4 years ago https://news.ycombinator.com/item?id=12350890
many more: https://hn.algolia.com/?q=Why+GNU+grep+is+fast