I was experiencing some bad Firefox performance this evening, so I did some research into how to speed things up.  I'll document my findings here, so hopefully it can help a few other people out too.

Keep in mind that these tips are useful only if you have some kind of broadband access -- cable, satellite, DSL, place of employment, etc.  I would not use this for dial-up users.

Also, my goal with this is to increase performance, and these settings work great for me.  They are not guaranteed to work great for you, but I can't see how it would hurt to try.

The first thing to do is to open up a new Firefox browser window (or tab) and enter about:config in the address line, then press Enter. 

If you see a huge listing of settings, you did the right thing.  If not, try again.

The settings is bold text are settings that have been changed from their default values.  It helps you see what has changed.

To change a setting, just double-click it.  True/false values will instantly change, and things like numeric values and character strings will open a dialog box when you double-click. 

Scroll down to settings that begin with the word "network".

Make the following changes:

• network.dns.disableIPv6: true
• network.http.max-connections: 32
• network.http.max-connections-per-server: 12
• network.http.max-persistent-connections-per-proxy: 32
• network.http.max-persistent-connections-per-server: 12
• network.http.pipelining: true
• network.http.pipelining.maxrequests: 4
• network.http.proxy.pipelining: true
• network.http.request.max-start-delay: 0

Then, right-click anywhere on the page and from the popup menu choose New -> Integer.  Enter the name as nglayout.initialpaint.delay and the value as 0.

After I did these things, my Firefox browser worked much quicker.  These values required some trial and error on my part, so perhaps I'll tweak them again in the future.