Brimstone does embed Unicode tables, but a smaller set than Boa embeds: https://github.com/Hans-Halverson/brimstone/tree/master/icu.

Brimstone does try to use the minimal set of Unicode data needed for the language itself. But I imagine much of the difference with Boa is because of Boa's support for the ECMA-402 Internationalization API (https://tc39.es/ecma402/).

Yeah, the majority of the difference is from the Unicode data for Intl along with probably the timezone data for Temporal.

Is it possible to build Boa without these APIs?

For the engine, the answer is yes, Intl and Temporal are feature flagged due to the dependencies. What I suspect they’re comparing above is the CLIs, which is completely different than the engine. I’d have to double check for the CLI. If I recall correctly, we include all features in the CLI by default.

That was an oversight, this is now under the MIT license!

Author here - very cool to see this get posted! Thank you @ivankra for adding this to https://github.com/ivankra/javascript-zoo and running those benchmarks, I really appreciate it!

This started as a hobby project that I've ended up putting a lot of time into over the last three years chasing completeness and performance.