FireTune helps you here - it includes all the performance optimizations. The only thing you must do is: make your selection. Firefox Optimizers does the work for you.Details on what exactly Optimizers does can be found in the help file.
In most of all cases you'll notice an improved browsing speed after optimizing Firefox.
Would you use a program that would reduce the memory usage of Firefox to 100-200 Kilobyte ? I have no idea how the Firefox Ultimate Optimizer is reducing the memory usage to this amount but the task manager is verifying the reduction. Firefox has been using roughly 40 Megabytes of RAM whenever I started it and one homepage was loaded.

After starting Firefox Ultimate Optimizer the RAM usage was reduced to 188 Kilobyte even with Firefox as the active window. The software does not have to be configured and sits in the system tray all the time.