You may be infected...
In IE go to Tools/Internet Options/Connections/LAN settings...does it show a proxy setting ? ?
"Use a proxy server for your LAN"? I'm not sure what you're talking about, but all the boxes are unchecked.
Run internet explorer without add-ons also and check the difference.
It loaded a "Internet Explorer is running without add-ons" page, which I assume is a system file, not a webpage (So it didn't need much power to load it). So I clicked the Home button like it said and it loaded in a second (which is probably half because it loaded IE already, and half because it didn't have add-ons). This I believe is irrelevant anyway, because I have not added anything for a long time, and it was perfectly fine the day before.
Update: I tried it today, with add-ons, it took forever but it finally loaded. I'm using it to post this now. So it loads, but it's extremely slow, and it wasn't like that the day before yesterday. I've missed my monthly cleaning (cache, etc) for a long time, I'll try to do it this week. Do you think that could be it?