I don't buy the "non performant code" argument. For the majority of applications it's not going to make a difference, and even stuff like an audio codec can be

I don't buy the "non performant code" argument. For the majority of applications it's not going to make a difference, and even stuff like an audio codec can be written in CoffeeScript: https://news.ycombinator.com/item?id=3371171 https://news.ycombinator.com/item?id=3371171