Why are images loading so slowly (on and offline)?

[LadyEnslain]

I had not had any problems with GIF's in the past. I connect via cable modem, and have a 2.4Ghz system. I downloaded Ulead Gif Animator, and created an animated Gif, which worked fine. I ftp'd it to my web server, and was able to view it perfectly.
The next day, and ever since, it isn't loading properly on my computer. It is fine from any other computer. I also cannot view the animation in real time from my pc browsing offline. It loads all the animation changes, and even when they are all there, it doesn't begin to go at the right speed, and my CPU usage skyrockets to 100% until I close the image.
It seems that large JPEG's are also loading much more slowly, on and offline.
Can anyone tell me where I should start in trying to correct this?

 

[LadyEnslain]

If I open the page in IE, it shows IE as using 97% of the CPU. If I view it in any other program offline that animates it, like ULead Gif Animator, then it shows that program as using 97% of the CPU.
I only really notice this on large image files, especially animated. Smaller files seem to take longer to display on my screen (again, on and offline), but don't affect my CPU usage once it's been loaded. Large animated gifs keep my CPU fully loaded until I close them.