Ubuntu Internet server problem

Hi all

I had setup an Internet server with ubuntu 8.04 having dansguardian,tinyproxy and firehol. I had setup two interfaces, one directing internal traffic and the other directly to the modem. So far so good but have two problems:

Browsing through this server is very slow
Cannot connect through port 3128...only 8080

Can you advise how I can solve these problems?

Thanks so much