The "build" step of an Electron app doesn't build Chromium, so this wouldn't be very feasible. Building Chromium requires an insane amount of computing power.

The "build" step of an Electron app doesn't build Chromium, so this wouldn't be very feasible. Building Chromium requires an insane amount of computing power. According to Google, a Chromium build on normal hardware takes 6+ hours. And alas, even if it was feasible to custom build based on what you need, it would have to be done via configuration--since there's no way to know at compile time which language features will be used, since your app could (and probably does) include remote scripts.