We should be more wary about premature optimizations, like in the article where caching in the original code made it slower! Always measure! Write naive code and measure, the JavaScript engines are very good at optimization, especially V8 and the others are catching up.

However when I do optimize JavaScript code I often get 10-100x performance. Usually by writing better algorithms. Eg no "black magic". So the original code in the article is not that bad, considering he "only" got 4x performance.

Moving to another programming language / WASM for less then 2x performance is not worth it - unless you hate JavaScript.