[qwertox]

Why is it so fast? Mainly because:

- It's written in Go and compiles to native code. [...] While esbuild is busy parsing your JavaScript, node is busy parsing your bundler's JavaScript. By the time node has finished parsing your bundler's code, esbuild might have already exited and your bundler hasn't even started bundling yet. [...] Go is designed from the core for parallelism while JavaScript is not.

- Parallelism is used heavily.

https://esbuild.github.io/faq/#why-is-esbuild-fast

[jamra]

Even in single threaded mode it’s fast. I think the main idea is that it creates an AST only a couple of times and then caches it so that the AST can be reused. Webpack on the other hand gets engulfed by its plugins which often do so multiple times.