Disable Firefox Prefetching
I love the Firefox web browser. Even more than Opera. However, Firefox tends to be a memory hog. The reason for this is that once you load a web page and begin viewing it, Firefox begins prefetching the pages that are linked to the page you're viewing. I can only assume that this is intended to make subsequent pages you click on load faster. This feature would have been great twelve years ago when everyone was on a 56Kbps dial-up modem but in today's world of multi-megabit broadband it really isn't needed.
One very undesirable effect prefetching has is to swell the amount of memory Firefox uses. Don't believe me? Load up four separate web pages in four tabs and leave them idling over the weekend. When you come back, don't be surprised if you see that the Firefox executable is using nearly 800 Megs of RAM. Yikes!
Even though you're probably reading this on a quad core Xeon with 4 Gigs of RAM, you may as well disable prefetching so you can put your memory to other use. To do this, first open a new tab or window. Next, in the location bar, type 'about:config' (without the quotes). This will bring up a list of internal Firefox preferences. You can tweak many aspects of the browser but we're interested in disabling prefetching. In the Filter field, type the word fetch. You should see a screen similar to the one below:
Simply double clicking the 'network.prefetch-next' value will set it to false (disable prefetching). Restart Firefox and look in amazement at how much less memory it consumes.
Now that it uses less memory, why not make it faster? Try this other tweak here.