HELPROOM ANSWER It may be that your PC doesn't have enough grunt to run Internet Explorer 8.0 quickly. Microsoft doesn't list minimum system requirements for version 8.0 on its website, but those for Internet Explorer 7.0 can be found here.
Another potential issue is that you have lots of bookmarks and add-ons. Try uninstalling these and reinstalling them one by one to see if one is holding things up.
You could add more RAM and use a faster hard drive, but you may be better off getting used to Google Chrome or giving Firefox or Safari a whirl.