[LennonCook]

Originally posted by T-D-C: I've noticed that aninmated gifs run faster on Firefox than in IE.

There's a good reason for that: IE slows them down. Basically, an animated GIF with less than a 100ms delay between frames is treated by IE as if it had 100ms delay. Firefox does exactly what the image file tells it to do. You notice similar with other programs - for example, MS Office is reported to do the same, but with the minimum delay being 10ms. Windows Picture Viewer does it right to my knowledge. I think other browsers sometimes try to follow IE's buggy (and non-standard) implementation, but they have trouble because it is completely undocumented, and can change at Microsoft's whim... and it has before: IE used to have a minimum delay of 50 ms.