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This scroll rate measurement turned out to be somewhat nonsensical. Can’t count the hours I’ve been analysing this scroll thing and there’s always something new to discover…

Only for smooth scroll on Firefox would it make sense. For other browsers, what appeared to be display refresh rate is actually just a measurement of how fast you can turn the mousewheel.

With IE something else is going on, I definitely count it as a new discovery (for me at least). When you write this, you would expect to get the scroll position at the moment the page starts scrolling :

$(window).scroll(function() {


All major browsers act as expected but IE returns a position after the scroll has finished! That’s why a single mousewheel turn is throwing out some odd numbers in the pen. Other findings – the amount that is scrolled with a single mouseturn :

  • FF a mere 95px in around 400ms
  • Webkit 167px in virtually 0ms
  • IE 222px in about 70ms

The latter explains the lagging mentioned in the previous post, I suspect…