There are a few different cognitive disabilities which could make a user desire to disable animation on sites: ADD, vestibular disorders[0], and epilepsy to name a few. Potential solutions: - implement the Reduced Motion Media Query introduced in Safari 10.1 [1]. - put CSS animation behind a preference and allow users to pref it off. - allow users to load websites "paused" and query them before repainting, then try to repaint the "after animation" state. - make Bug 1278950 available to all users (I hear we're separating out the dev tools though so this might be impractical) Many of these users currently solve the problem by browsing with javascript disabled which is an increasingly difficult way to use the web :/ [0] http://a11yproject.com/posts/understanding-vestibular-disorders/ [1] https://developer.apple.com/library/content/releasenotes/General/WhatsNewInSafari/Articles/Safari_10_1.html#//apple_ref/doc/uid/TP40014305-CH12-SW23

This is a hard problem to solve in general. I think this is effectively a dupe of bug 456620, so I'm duping. For Firefox itself, bug 1352069 was recently fixed, though there may be more animations that will need to be made subject to the pref. For the reduced motion media query, I expect you'd want to file a separate bug in Core :: CSS Parsing & Computation. I don't think that alone solves the problem - for the browser-as-a-user-agent model, we should also change how we deal with pages that define transitions/animations without using that media query to disable them (which, as comments in bug 456620 make clear, is not an easy problem to solve in a general fashion).

Moving from Core::Untriaged to Core::General https://bugzilla.mozilla.org/show_bug.cgi?id=1407598