Let me quote a post for you
Of course it's much faster. HTML5 Apps are written in Javascript and interpreted by the browser's JavaScript engine, whilst native apps run in native machine code (IOS "C") or at least as compiled byte code (Android "Java"). Also, native apps have much more possibilities to access the system they are running on (sensors like GPS, camera, file system, ...) through the APIs provided by the OS, whilst HTML5 apps are bound to the HTML5 API which is a small subset.
url=http://stackoverflow.com/questions/12098595/native-app-faster-than-html5]source
That explains much of it
Now listen , don't blame C2 , C2 is a wonderfully optimised engine , blame HTML5 , it's known in the industry that "some" technologies sacrificed performance for portability , now that's the case of Java , but it got heaps better now that it's mature , same thing goes to HTML5 , let it mature a bit ... and stop blaming C2
+ Your card is probably blacklisted or something , and that may be the reason you can't squeeze much performance out of it , remember , if WebGL isn't supported , you won't get accelerated graphics , and that can affect your performance , thus , try your games on better rigs and maybe you'll get better result ! <img src="smileys/smiley1.gif" border="0" align="middle">