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.
If you want to enjoy both smooth scrolling and responsive input method in a webview, you need to juggle between those layer types.
LAYER_TYPE_HARDWARE enables smooth hardware-backed scrolling but glitches badly when the soft keyboard is visible (no resizing/panning of the webview, multiple seconds of delay between key type and text updates inside textfield forms).
LAYER_TYPE_NONE makes scrolling in the webview unbearably stuttering, but at least the soft keyboard becomes responsive, the webview pans correctly to show the field in which you're inputting text, and the key types are instant.
On top of that, there is the problem that you don't have access to keyboard show/dismiss events, so you have to inject javascript code to catch those in every page you plan your webview to display. This is at least the case on the Motorola Xoom and the Acer Iconia tablets running the latest versions of honeycomb.
There must be a different underlying issue there. Showing a keyboard view should have no performance implications on a web view. Similarly drawing text into a texture tile should not take "multiple seconds of delay".
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.