I've been having this constant issue in Safari on my 2014 5K iMac running OS X Sierra, latest version. Basically, the gifs etc get cut off halfway. e.g. check out this site, and scroll down to the gifs. You can see half the image is missing (if you're seeing what I'm seeing). This doesn't happen on EVERY site, - but on a lot of them, yes.It's not just gifs, but other embedded images etc. But this is a good example. http://gizmodo.com/first-self-driving-car-race-on-a-pro-track-ends-with-a-1792530922 They display just fine in Chrome/Firefox, but Safari? Nope. Any idea how to fix this?