Indeed, Apple's Mac OS X QuartzGL framework (GPU accelerated drawing/rasterisation) is slower than the equivalent CPU-based Quartz framework in may cases.
You're being shafted by downvoters who don't really know what they're talking about.
Turning on hardware acceleration doesn't cause all Android views to be FBO-backed. You still need to toggle the layerType to LAYER_TYPE_HARDWARE on each view, as far as I'm aware. I think the G+ post is a little disingenuous in that regard.
Google suggests toggling between LAYER_TYPE_NONE & LAYER_TYPE_HARDWARE pre/post animations. This need to actively manage view cache behaviour probably leads to developers being unaware of what to do.
Also, if you're calling an Objective-C method and dynamic dispatch is causing measurable performance issues, you can cache a pointer to the C function that backs the method (called the IMP) via the class_getMethodImplementation() runtime API.
That's pretty neat! An unfortunate side effect is that running Mobile Safari unsigned negates the 'dynamic-codesigning' entitlement, which means that Nitro is disabled.
That said, a WebGL-enabled UIWebView running in your own app will also not be Nitro-enabled. I've run the PhiloGL spinning world demo on my device and it's running at 40fps, so simpler demos may be possible without a Nitro to boost things a bit.
You're being shafted by downvoters who don't really know what they're talking about.