Please be careful with the "close to C in speed" claim.
There are only a very small number of languages that can legitimately claim that (C++, Fortran, and sometimes Ada). Java is not one of them. JavaScript is surely not one of them, even with the latest versions of V8.
The only time we see performance remotely close (which still usually means several times slower, at best) to C is for extremely unrealistic micro-benchmarks that have been very heavily optimized to a state where they don't at all resemble real-world code.
We have had Word Processors and Spreadsheets in Javascript (Google Docs), 3D and 2D games, and even a h264 decoder and a PDF renderer. Heck, they have ported QT to Javascript, and the example applications run at a very acceptable speed. None of the above are slow.
So, no, it's not true that V8 is only fast in selected "microbenchmarks".
You might not do scientific applications or NLE video editing with it, but for everything else it should be just fine.
>'Very acceptable' speed isn't what consumers are looking for when comparing battery life and wall-clock performance between competing platforms.
Where does the idea come that V8s and co very acceptable speeds come at the expense of battery life and wall-clock performance???
Not to mention that people are using far less capable web apps in the mobile and desktop space now (i.e pre-asm.js javascript), so the increase in speed due to the asm.js/optimisation standardisation would only make battery life and wall-clock performance better.
There are only a very small number of languages that can legitimately claim that (C++, Fortran, and sometimes Ada). Java is not one of them. JavaScript is surely not one of them, even with the latest versions of V8.
The only time we see performance remotely close (which still usually means several times slower, at best) to C is for extremely unrealistic micro-benchmarks that have been very heavily optimized to a state where they don't at all resemble real-world code.