It hasn't been updated since February 2005, but 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 about 30MB of RAM, the program dramatically improved start-up times on Firefox when loaded with tabs and extensions.
How dramatic were the improvements? Without using the Preloader, it took 32.1 seconds for Firefox to open, and 2 minutes, 34.2 seconds to finish loading all the tabs. With the Preloader running, Firefox opened in 7.8 seconds, with another 1 minute, 36.7 seconds to complete all the tabs. 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.