You really want every web page to be shipping their own JIT (or forcing users to grab it from a CDN)? JavaScript JITs are huge. Also, the idea that you can jus

You really want every web page to be shipping their own JIT (or forcing users to grab it from a CDN)? JavaScript JITs are huge. Also, the idea that you can just ship a JIT in Native Client and have the performance not hugely regress is unproven. Modern JavaScript JITs are fundamentally based around self-modifying code (look up how PICs work). NaCl penalizes self-modifying code by requiring that it run through a verifier. It would require a lot of engineering effort just to avoid huge JS regressions (like this 2.5x slowdown from a year ago [1]); why not spend that manpower to improve JS engines? [1]: http://code.google.com/p/nativeclient/issues/detail?id=731 http://code.google.com/p/nativeclient/issues/detail?id=731