we facing performance issues where we have some server which are behind PIX firewall. The latency to the servers increase at certain times for 2-3 hrs and this goes upto 30-40ms while during other times this remains 1-2 ms. The performance with other server on the same LAN whose traffic is not passed through firewall remains normal. There is nothing abnormal with the server or any performance issues. We checked infrastructure and couldn't see an issue. Is there anyting overlooked and help to resolve the issue.