Perhaps you could try running IE8 in no add-ons mode. Start -> All Programs -> Accessories -> System Tools -> Internet Explorer (No Add-ons) to see if one is causing the problem. If this fixes the issue, then go to Tools -> Manage Add-ons and change the Show setting on the left to All Add-ons, then select all of the add-ons listed and click Disable All. You can then enable the add-ons one by one to find which one is causing the problem.
Or, if you have any add-ons with a large load time (more than .2 seconds) enabled, you may want to disable them and see if that helps with your loading issue. Just go to Tools->Manage Add-ons to do this.
Hope that helps.