Since azakai is too humble to mention his own qualifications, I want to point out that is the author of the Emscripten LLVM-to-JS compiler, and the BananaBread first-person-shooter demo linked above, so when he talks about the limits of JS performance compared to C, he really knows what he's talking about. :)

Well, I could agree if I saw any computational-heavy JS application (and not a microbenchmark) doing well compared to native counterpart, especially on multicore. So far, I found only the one I cited - and the fact is, it is damn slow.

While JIT is getting better over time, you are soon going to hit the law of diminishing returns - the JIT is already extremely sophisticated, but still being a few times slower on average even than JVM. And JVM has it much easier, because it has full explicit type information, while JS has to first figure it out. So I wouldn't expect miracles here.

> Well, I could agree if I saw any computational-heavy JS application (and not a microbenchmark) doing well compared to native counterpart, especially on multicore.

For example, BananaBread compiles 120,000 lines of code of a C++ 3D game engine, including AI and physics and so forth. It also uses 3 cores during startup processing

The difference between JavaScript and C++ is less than one order of magnitude, and note that this is a hard case to optimize for JS engines since LLVM inlining creates huge functions that JS engines just give up on optimizing currently. So that the game ends up still running as fast as it does in JS is a nice surprise.

There are also lots of other compiled examples of real-world code, like Box2D and Bullet. Typically the speed of JS compared to C is 5X-10X slower, again, much of it because of large functions not being fully optimized.

If you're working on Bananabread, can you check why it's not working on Chrome, the latest stable version? I get an Oops message. I use Windows 7 x64, Core i7 laptop with Nvidia 555m GT .Also just installed Nvidia's latest driver, though I haven't rebooted yet. Could that be it?

Have you enabled mouse-lock in chrome://flags ? It talks about this on the page, if you're curious.

I am aware of a bug in Chrome where the Chrome tab will crash after you play for a while or reload the tab. But in a new tab you should be able to play for a few seconds ok - is that what you are experiencing?

Just swap base e for base 10, and boom, twice the orders of magnitude.