The site loads perfectly well for me, I doubt that that one item will make much if any difference at all. Compression and cache are usually the most important factors that you can manage under your control. Your hosting makes the biggest difference in the end.
As Roger said this is such small fix it wouldn't be that noticeable. But if you do decide to go change it, go with a JavaScript image rotator rather then a .gif image, it will look cleaner.