How to make my Network Fast.?

In my company we have a domain server and a database server.Now DHCP is not maintained.We use static IP.Our problem is that The Internet connectivity is given through database server and its been shared among the employees throug proxy i.e. the ip of database server and using the software CC proxy.

Now the LAN network is going too slow.

Can u plz suggest me any way out forf making it Fast.
The servers are with 2003
and clients are XP/