I've been using this tweak for some time, but don't recall if I ever shared it with you folks. (or if I did, it was a long long time ago)
1. Type "about:config" in the address field.
2. Set the value of network.http.pipelining to "true".
3. Set the value of network.http.pipelining.maxrequests to "100".
4. Set the value of network.http.proxy.pipelining to "true"
5. Set the value of nglayout.initialpaint.delay to "0"
If the variable isn't there, you'll have to create it yourself. To my knowlege, only "nglayout.initialpaint.delay" isn't in Mozilla by default. (for those of you that have to create it, keep in mind that it uses an integer value so you'll have to use the integer option.)
To add a variable, all you have to do is right-click (anywhere in the variable listing) and select new. Pick the type of variable, and then give it a name and value. All changes take place immediately.