It hasn't been updated since February 2005, but the free Firefox Preloader continues to help users who want faster boot times while maintaining a heavy load of tabs and extensions. Weighing in with an installer at 840kb and using around 30MB of RAM, the program gave me dramatically improved start-up times on a fully loaded Firefox 3.0.7.
Somebody running a clean, unencumbered version of Firefox probably wouldn't find Firefox Preloader all that useful, so I tested it against Firefox with 22 extensions and about 40 open tabs. The extensions ranged from the bulky Cooliris to the svelte AutoCopy, while the tabs included everything from text-heavy, easy-to-render message boards to the main Facebook page and YouTube.
How dramatic were the improvements? Without using the Firefox Preloader, it took 32.1 seconds for Firefox to open, and 2 minutes, 34.2 seconds to finish loading all the tabs. With Firefox Preloader running, Firefox opened in 7.8 seconds, with another 1 minute, 36.7 seconds to complete all the tabs. I tested the times by hitting a stopwatch at the same time as I opened Firefox, so my times might be off by a couple tenths of a second, but even with factoring in the imprecision of the test, the results are still impressive.
Firefox Preloader is not otherwise laden with options. You can set it to run when you turn on your computer, and it installs a convenient system tray icon for accessing it on the fly. From there, you can unload the preloader, which clears out the program from the list of active tasks. And you can reload it, which dumps it from the active cache and then reloads it.
The Preloader doesn't play well with certain browser functions, notably when Firefox restarts after installing an extension or theme. It almost certainly adds at least a small amount of time to the computer's boot cycle, since it's one more thing that needs to load before Windows is ready to go. But for users who want to have their cake of extensions and tabs and eat it, too, Firefox Preloader remains a reasonable way to gain back more than a few precious seconds.