Not sure why my sincere question about the state of browser execution environment got downvoted, but the general concerns I raised in my first comment weren't about incidental complexity or hassle. They matter and it's great that clojurescript helps with those two. The concern I voiced was about maintaining realtime performance of a responsive user interface. The key issue is that you have a single event loop that all visual and human interactions need to be handled by because that's the only thread that can interact with the DOM. It's just way too easy to block that thread and cause the app to become unresponsive.