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.

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.