Here's something for broadband people that will really speed Firefox up:
Type "about:config" into the address bar and hit return. Scroll down and look for the following entries:
Normally the browser will make one request to a web page at a time. When you enable pipelining it will make several at once, which really speeds up page loading.
Alter the entries as follows:
Set "network.http.pipelining" to "true"
Set "network.http.proxy.pipelining" to "true"