There's no secret sauce Just lots of time spent profiling and trying things On the runtime side, JavaScriptCore/WebKit's team are extremely receptive to feed

There's no secret sauce Just lots of time spent profiling and trying things On the runtime side, JavaScriptCore/WebKit's team are extremely receptive to feedback, especially performance-related. Today, @Constellation made `Promise.all` about 30% faster https://github.com/WebKit/WebKit/pull/3569 https://github.com/WebKit/WebKit/pull/3569