Gmail as written in 100% Closure Compiler code, Closure Compiler was invented for Gmail. Simple fact is, Google is a Java oriented company. Inbox uses lots of

Gmail as written in 100% Closure Compiler code, Closure Compiler was invented for Gmail. Simple fact is, Google is a Java oriented company. Inbox uses lots of components and shared code across the company that are based on Java. To use C# or C++ to do it would rewriting a lot of code that already exists. JS performance is not the gating factor for the Web client in most cases, it's rendering and startup (code size). We run expensive calculations off the main thread in a Web Worker anyway. The translation of Java to Objective-C could have been to C++ as well. I started prototyping something a while ago that does such. Objective-C makes more sense, because for iOS, the front end developers get to consume 'idiomatic' code that looks like they had hand-written it and it meshes well with other tools, and would work with Swift too.