Marti's blog

Besides its basic configuration panels, Firefox offers more tweaking options by manually editing a sort of internal registry (in some ways similar to Windows' registry, but without a hierarchical organization). You can access and edit all possible configuration keys by typing about:config in the address bar. If a specific key doesn't exists already, you can create it using the context menu.

Here's a few key that I always change :

• network.prefetch-next Firefox allows web pages to mark some of their links as prefetch. When such a link is encountered, Firefox will start loading the target URL in the background so that in the event that you click on it, all the data are already in the cache and loading is faster. Now, do you really want your browser to silently fetch stuff at the order of any page without you even knowing about it ? Do you want it to use your bandwidth loading stuff that you are likely to never use ? I don't, so I set this value to false.
• config.trim_on_minimize Firefox can take up a lot of memory. If this value is set to true, Firefox will release most of the memory it uses when it is minimized. It's supposed to make things a bit slowed when re-opening Firefox's window, but I haven't noticed any slowdown.
• network.http.pipelining and network.http.proxy.pipelining Pipelining is a HTTP 1.1 feature that allows a browser to request several files sequentially without waiting for the first one to be received (and as such greatly boosting page loads). Supposedly some sites might break if you enable this, but version 1.1 of the HTTP protocol has been around since the end of the 90s, and I haven't noticed any issue either (but I did notice quite a speed up on some sites). So set both of these to true.
• network.http.pipelining.maxrequests This works with the previous pipelining settings, and indicates how many files can be resquested sequentially. 8 seems to be a good value for it.