Internet Explorer 8 suddenly slows down to a "crawel"

I have IE 8 on my WinXP Pro SP3 computer. IE 8 used to run faster than
Firefox on my computer. But starting yesterday morning, IE 8 suddenly
starting taking minutes to open up to my home-page. But the real slow down
was when I tried to navigate to other web-pages. On some of my favorite
web-pages , it would take several minutes to load a web-page that used to
take only seconds to load.
When I started IE 8 to a about:blank web-page , it opened much faster than
my home page did. But navigating to other web-pages was just as slow. And
opening up IE 8 to my homepage, with all "add-on's" disabled was just a
little faster , but not much.
However , my Firefox browser is not affected with what ever is slowing
down IE 8 .
And I also began having problems connecting to "Windows Update" . It was
impossible to connect to Win Update via "help and support" . But I was
finally able to do so within my IE 8 browser. That's when IE 8 was still my
default browser.
Any feedback on this IE 8 problem would be very appreciated . I do like IE
8 better than Firefox , but until I can find a fix for my IE 8 problem , I'll
have to use Firefox as my default browser.
Thanks.
--
your friend,
Larry