...how about a mod, like "do not show .gif avatars"?
How about a browser that allows you to disable gif animation?
*cough*Opera*cough*
Or, if your browser supports site-specific stylesheets, just add one for the forums with
img[src$=".gif"] { display: none; }
That means
img tags with a
src attribute that ends in
.gif.
Your browser does support CSS, right?