Here is a handy tip for dealing with a site that has animated GIFs, pressing ‘ESC’ key will pause animated GIF’s on a page. This works in both Firefox and Internet Exploiter. Note: in order to ‘resume’ the animation you will need to refresh/reload the page. You can test this out with the image below:

Firefox 1.X and 2.X users have some additional options via an about:config tweak:
- In a new tab type about:config in the address bar and press enter
- In the filter field type animation
- In the results listed double-click on image.animation_mode
- In the pop-up box type in one of the following:
- none — will prevent image animation
- once — will let the image animate once
- normal (default) — will allow it to play over and over
Edit: Once setting does not appear to work in later builds of Firefox 2 and does not work at all in Firefox 3.
Tip Source: CyberNet News

The ‘ESC’ key works great for me! Wish I’d known about that a long time ago. Thanks!
Need help to get my gifs to animate.
I checked the above and it is set to normal so it should animate, but gifs do not for firefox 2.09 nor my explorer 7.0.
Any help would be appreciated.
Well i just change my config for 1. thanks
Animatd GIFs in my firefox broweser run faster than IE. Any ideas?
This may sound strange, but could you tell me the name of the person who created the animated gif in your entry, so that I know whom to credit on my livejournal userinfo?
Is there a way to restrict the image.animation_mode setting to a specific domain?
E.g. image.animation_mode = none
for domain foo but
image.animation_mode = normal
for all other domains.
@Bob, interesting idea. I don’t know of any way at this point. I am not sure if it is something that could be possible via a GreaseMonkey Script or an add-on.