I normally keep anywhere from 30-50 tabs open in Firefox at any given moment. There are two specific downsides to this. For one, restarting Firefox takes forever, because the browser has to load 30-50 web pages at once (although this isn’t really a Firefox-specific problem; any browser would take a while to open 40 pages at once). The second problem is that Firefox often eats RAM like candy. It’s not uncommon for Firefox to use anywhere from 1GB to 1.5GB of RAM on my system.
But the folks at Mozilla added a nifty tweak to Firefox 8. If you go to the General tab of the Options pane, you’ll see a new check box that says “Don’t load tabs until selected”:
If you check this box, Firefox will keep track of which tabs you have open, but won’t actually load the page until you select its tab. This tweak was added to speed Firefox’s start-up time (and, as such, works beautifully). But the tweak also greatly reduces the amount of RAM Firefox uses in general. When I enabled this option a few days ago, I had 48 tabs open, and Firefox was using 1.2GB of RAM. After restarting, I selected a few tabs and Firefox was only using 443MB of RAM. I’ve had the same session open for three days now, and have opened and closed several windows (and still have the same “base” of 30+ tabs open) and Task Manager reports that Firefox is “only” using 553MB of RAM.