IE8 is only slow with Spybot immunization, not any other Anti-Spyware or Anti-Virus programs, I run, which are:
Norton Internet Security, Norton Safe-Web, SpyBlaster, Super Anti-Spyware, Norton Anti-Bot, Malware Bytes Real Time, Win Patrol do not slow down IE8 on XP SP3 or Vista, IE8 is only slow with Spybot immunization.
So that tells me SpyBot has problem.
I think it is the 10,000 items in the Hosts file immunization, is causing
the majority of the problem.
I do not think Microsoft will fix this issue as they do not recommend using
the Hosts file for protection activities.