Squid is a caching proxy and conserving badwidth application for the Web supporting HTTP, HTTPS, FTP, and more. It reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. Squid has extensive access controls and makes a great server accelerator. With Squid, you can reduce the network/internet traffic by 30% or more from normal usage (without squid) and enhance respone time.
Step-by-step instructions on how to install Squid on FreeBSD can be found here.