It’s slow as molasses in some parts though. (Deliberately, it’s a trade-off.)
The Unicode part of ICU shouldn’t be that large, however (on the order of hundreds of kilobytes), it’s the locale data that’s big[1]. Does Bun implement ECMA-402 internationalization? Even without locales, one of the largest parts of ICU data is normalization and casing tables, which I think bare ECMAScript does not require. (It does mean bare ECMAScript cannot adequately process Unicode text, but meh, you get what you pay for.)
[1] https://unicode-org.github.io/icu/userguide/icu_data/buildto...
