If you use this, me and my Firefox mobile will hate you.
Also: Funny how something which was utterly normal on a C64 (and even more so, the Amiga) back in the 80s is suddenly magically hip after Apple used the word in a keynote about iOS7.
The parallax trend has been happening for months on web pages.
Apple will popularise the trend in iOS apps though that was related to device motion and is bit different to what's happening on the web.
On the point of Apple, usually this sort of parallax doesn't work within Safari on iOS devices as scrolling in iOS pauses the main run loop of code. Looks like they've found a work around here, so kudos it's actually functional, but scrolling performance appears to suffer terribly.
No there is no work around. Only option is to use your own implementation of scrolling or 3rd party library. Looks like demo is using some sort of library that is why scrolling performance is laggy.
Also: Funny how something which was utterly normal on a C64 (and even more so, the Amiga) back in the 80s is suddenly magically hip after Apple used the word in a keynote about iOS7.