I sent an email to the Register about one of their pages with animated gifs in an ad. Running debian / KDE/ Konqueror, it instantly took my cpu load up to 100% and it stayed there (at least on gkrellm) until I moved from the page. The same page in Mozilla was at 50 -60%
That would account for slow input or scrolling Funny, it was just one ad, and other pages that also had animated gifs were only in the 3 - 4 % range on another machine (windows) the same page in IE had the gif running MUCH slower
