I recently shot a video called "Another way to speed up Firefox," and a couple of you e-mailed me for a transcript of the steps! Without further ado, here they are:
First, open Firefox, and type "about:config" in the address bar. In the filter box here on the top, type "network" and scroll down to "network.http.pipelining".
Then, double-click the line to change the value from "false" to "true." You can also right-click and select "Toggle" to do the same thing.
Now, go to the next line (network.http.pipelining.maxrequests) and change the value from 4 to 10.
Finally, restart Firefox to apply the changes! You should notice a change in the speed right away.
Hope this helps!