You should only run 1 firewall and 1 antivirus so this is probably what is causing your slow PC issues.
If you want free security software then AVG and Comodo are good free products. You could also try Zone Alarm for a firewall, it's pretty good. BitDefender do a free antivirus as do Avira and Avast.
The rule is though, just one firewall and one antivirus.