In this paper, the authors investigated the firewall security and performance relationship for distributed systems. The relation between the security and performance efficiency is presented through different scenarios and the relationship between security and performance in firewalls is evaluated. Emphasis is on the relationship between network security and performance; the effects of firewalls on network performance. Various scenarios were evaluated through simulations to show the effects of firewalls on network performance. The result shows that the network security does not have a direct correlation to network performance.