For those who want to package their html5 game as an app (I certainly do) there is CocoonJS and Crosswalk (based on Chromium). I did find CocoonJS significantly faster than Chrome, but it still failed to produce sufficient speed on my tablet.
Since WebGL is virtually identical to OpenGL ES 2.0, which is available on any recent Android device, I was surprised with the low performance. I've seen my native apps do so much better. WebGL on mobile should be a better fit than WebGL on desktop, not worse. My suspicion is that Chrome/Chromium has a lot of security/safety/sandboxing overhead, and/or uses a renderbuffer compositing scheme for handling canvas scaling and HTML element overlays that doesn't play well with cheaper devices. CocoonJS probably has some of the same problems, in particular with regard to compositing.
At this point I have two games and some pixi.js and phaser.js examples running, and it looks good! I managed to whittle down the base APK size to 1,3 Mb. I've tested it against Chrome on several devices, but I guess evidence remains somewhat anecdotical. My experience is that gles.js indeed runs faster than Chrome, speed difference varies across devices. It's like between 50% faster and 5 times (!) faster. It also runs smoother, that is, where I often see small hiccups in Chrome even on fast devices, gles.js runs the same code silky smooth 60fps, which has become the norm on Android nowadays. And my limited testing with CocoonJS also indicates it's faster than their implementation.
I am happy to report that my second game, Tsunami Cruiser, also runs! I quickly made a gamepad port for the Ouya. I was quite surprised it runs at 60fps on the Ouya, as this beast is not well optimised and has like 2,000 particles and 100s of line segments and tons of trigonometry. CocoonJS runs this at around 40-50 fps with hiccups. Not bad, but the hiccups look terrible. I also ran it on the Moto G, where it also runs at 60fps (note you cannot move yet on Android). CocoonJS manages no more than 30fps on the Moto, and Chrome no more than around 20. So again, gles.js is consistently faster.
I know that Scirra will stick to slow CrossWalk because it's just easier for Ashley, since he is not making games and thinks that C2 devs can wait forever. But maybe @Ludei could contact gles.js author and use his knowledge? Or anyone else? Just dreaming...