For sometime now, when accessing email websites such as Yahoo and Hotmail, it would be soooo slow on and off for like a few weeks.
I finally figured it out. When Bitdefender is installed, it updates (I think XML) files to the /System32 directory. Vista upon detecting this requires the two new KB patches be installed. Actually, when the first one is installed it works fine, but once the first patch is installed, Vista requires the second one to be installed. Once this happens, accessing Yahoo and Hotmail websites are extremely slow. These patches are used to update XML files for Vista.
So all I did was reinstall Bitdefender and ignore Vista's request for the KB patches to be installed.