Earlier quoted context omitted.
As I understand it, potential performance gains are higher than 2x, and we're still in a pretty early stage. It depends on your application. Also, as has been mentioned by others, WebAssembly could perhaps evolve to take a greater role, leading to a greater potential impact of performance gains. Finally, if the complexity does in fact outweigh the benefit, the idea would eventually fade away. So far it looks promisin…
Where does even the 2x come from? Currently it looks very much like 1x vs integer hinted JS code like generated by asm.js.
These are already old numbers, and section 7.3 says 33.7% more efficient. Were one to run updated numbers, and use more than Chrome and Firefox, I'm pretty sure the numbers would be better still.