Unfortunately, I had the same problem with ZA free firewall and switched back to Windows Firewall within hours.
You went back to windows firewall???? Are you insane????
I don't mean to be dramatic, but the Windows firewall is crap.
A good, third party firewall (Like Zone alarm) not only blocks incoming traffic, but outgoing traffic as well. The windows firewall, on the other hand, only
blocks incoming traffic.
"Why should I care?" you ask? Well, if by some chance you get infected with something, the windows firewall will not stop the spyware/malware, etc. from interacting with the infecter, may it be a person or a corporation. In other words, Windows firewall will let the installed spyware spy on you!!!!
A third party firewall, however, will prevent the spyware/malware from reaching its host; the firewall will block it from "talking" to those who want to spy on you.
I'm not sure how to correct speed issues with Zonealarm, but I know of a workaround; install another firewall.
On my laptop, Zonealarm works great; I have had few troubles with it, and they mostly relate to updating, not how it works. However, when I installed it on my parent's PC, not only did the internet lag, but sometimes, they couldn't even get
online! I uninstalled Zonealarm, and installed a new firewall; Sygate Free Firewall. It worked. My parents PC is running smoothly now!
Here are some good, FREE, applications to look at:http://www.bleepingcomputer.com/forums/topic3616.html
Scroll down a little, and look at the "Firewalls." Find a different one, and try that one. Don't leave your computer exposed!!!
*climbs down off of soapbox*