After installing ZoneAlarm version:8.0.065.000, web pages were very slow to load using either Firefox or IE. I attempted to do a system restore, but I wasn't able to do that after 2 attempts. So, I unchecked the Zone Alarm Spy Blocker. But that didn't help.
So, I uninstalled the Zone Alarm Spy Blocker toolbar, and now web pages load quickly.

Operating System:Windows XP Home Edition
Software Version:8.0
Product Name:ZoneAlarm (Free)