Here a tweak which i found while surfing net....i Hope this is useful for you to make your firefox faster ! :)
1. Type "about:config" in the address bar of mozilla 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.
2. Alter the entries as follows:
Set "network.http.pipelining" to "true"
Set "network.http.proxy.pipelining" to "true"
Set "network.http.pipelining.maxrequests" to some number like 30/40/80/100. This means it will make 30/40/80/100 requests at once.
3. Lastly right-click anywhere and select New-> Integer.
Name it "nglayout.initialpaint.delay" and set its value to "0".
This value is the amount of time the browser waits before it acts on information it recieves.
If you're using a broadband connection you'll load pages 2-100 times faster now.~! :)