Just on a whim, I loaded a page that had T Paul's Avatar on it (with the cat winking) in three different browsers - Internet Explorer 5.1 (for MAC), Netscape 6, and Opera 5. In Explorer the winking speed was just about right, I think. In Netscape, twice as slow to execute, and in Opera you had to look quick to see that it moved (if YOU blinked you would miss it). Just thought I'd throw that out there to say that not only do browsers reproduce web pages and static artwork differently but also you can't depend on the speed of GIF animations to be anything like how you created it either. What fun!
while I was whimming, I copied the address for this post (to check out MY avatar speed for comparison). Oddly enough (to me, anyway) it remained fairly constant in each browser. I can only conclude that the more frames you have in your animation the more faithfully the animation is rendered. BUT, the longer it will take to load. Just some more info for those who would design websites to pull their hair out over.