That's mostly because its a library, and so most of the optimizations you're getting are purely local in-method and no dead-code pruning. Where Closure shines

That's mostly because its a library, and so most of the optimizations you're getting are purely local in-method and no dead-code pruning. Where Closure shines is building an app whole-world, compiling both the client code, and library code together, then it can prune away all unused methods in the library.