Stickiness and lumpy bits
I really enjoyed Andy Davies' talk on mobile site performance at Port80 2013, but one fact in particular stood out for me…
Facebook artificially slowed down scrolling from 60fps to 30fps. User engagement collapsed.
This is a great example of why animation (or movement) should be considered when designing websites, even if, as designers we aren't in complete control of the results.
A lot of the ways in which a user might experience movement is embedded into the browser and we should try our best not to interfere with the way it moves, by creating pages that render poorly. This is true whether we are adding new animation or not.
Stickiness and lumpy bits are a massive turn off, so it's important that we don't end up scaring people away.
Check out the rest of Andy's slides