I just tested a page I created on mobile (iPhone 6 Plus) and it seemed to feel very heavy.
What I mean is that 1) the scroll does not seem to glide smoothly and works only in jerks 2) it does not scroll to the bottom easily and requires many flicks to move towards the end. And the page has barely any content on it.
Other pages e.g. CNN etc. scroll very smoothly, so its not the iPhone.
By default, iOS devices don’t use momentum scrolling for HTML elements other than the body element.
The scrollable element in your project is the scene, not the HTML body.
So you must enable momentum scrolling for the scene, for example, by adding the following script to the scene activate event:
function onSceneActivated(doc, e) {
this.dom.style.WebkitOverflowScrolling = 'touch';
}