Closure Compiler: High-level overview of a compilation job

It depends on the code base. When I've migrated from js code base with 100% gcc type coverage to TypeScript, gcc(without tsickle) in advanced mode stopped rewriting many methods into simple functions, didn't minified many symbols, with 100% type coverage gcc minified all symbols.

When I've tried synthetic UI benchmarks, code with 100% type coverage on desktop machines had the same performance, on old mobile phones it was 0-10% faster(depends on the use case).

Minified code size with 100% type coverage were slightly smaller on small projects, but with the API for building UI Components that I've used, minified code with 100% type coverage should be significantly smaller on a large project.

Didn't know it was used so much out of Google, that's a lot of downloads and that just for NPM, I would guess maven and direct downloads are even bigger? not counting clojurescript and scalajs which bundle closure in their compiler.