On iPhone and iPad, i.e. IOS devices, in some cases the smooth, accelerated scrolling is not working. Instead the web page feels “lagging”, slow or stuttering and won’t continue to scroll in the smooth accelerated way you are used to.
To solve this, make sure to use overflow-y: scroll; (not auto) and apply -webkit-overflow-scrolling: touch; to body and possibly other elements. If it is not enough to apply it to the body you might need to also apply it to your div:s, like the wrapper div and so on.