why do certain gifs make my computer slow to a halt?

[dpopiz]

I have a fast system, but I notice every once in a while, a gif on some web page will slow my comp down so much it takes a few seconds to even register a button being clicked
why?

 

[NuclearFusi0n]

stop using radeon drivers that are older than sin.

 

[Superwormy]

Animated gifs combined with Internet Explorer sometimes seriously uck up and slow down teh computer.

Only cause Internet Explorer blows though.