News to me, but the Safari browser and some Apple products apparently can’t handle GIF animations either at all, or, even when they can handle them, do so with some degree of difficulty. A little bit of web research suggests that Apple browsers and devices have had this problem in one form or another since… 2004! Also had a bit of hinkiness on my own main browser (Firefox on Windows 7), though nothing too severe. Anyway, I’m putting the recent GIF pieces off the front page, with a warning to Safarists.
Additional: They seem to work fine on Safari for Windows 7 – so it could be an Apple OS + Safari problem mainly.