Tweak | How to optimize FireFox to use less Memory

I had been facing a lot of issues lately with Firefox when I've multiple FF windows and tabs open. Usually I'd have atleast 4 FF windows: Markets, Code/Tech Search, Reader/Blogs, Misc opened at my Desktop, each having half a dozen tabs.
With my belief that FF is less buggy (or so you'd say I'm biased towards open source browsers) and has less mem leaks than it's in-famous counterpart IE... I've been living pretty happily with this browser for some time until recently when I started facing heavy memory usage issues (maybe it's normal but I still wanted to squeeze it down when FF is resting at the task bar). Googled out one such solution:
Courtesy: This web-link

Steps:
Note: Just check your FF memory usage from task-manager for the no. of win/tabs open(firefox.exe)
1) On the website url toolbar type about:config
2) A page full of words will show up. Right-click anywhere and choose New -> Boolean
3) For the name input type "config.trim_on_minimize"
4) Select True
5) Restart FireFox.
6) Ctrl + alt + del (this opens your task manager)
7) Go to process and choose your Firefox process (usually called firefox.exe)
8) Look at the Memory Usage Column (average is 20,000-40,000, for me it was 100,000 for two windows having 2 tabs each, other things could also account for heavy mem usage; one being lot of script based, data-intensive, client-side calc, auto-refresh websites)
9) Now minimise firefox and you will see the memory usage to be less than 10,000 (for me it came down to 45,000).

Normally, the memory usage is bound to go down for most apps with Win-key+D option when you put everything un-used back into the task bar. But, if things still doesn't go better with FF, I believe this tweak is for us to use.

Just a follow-up: To have more such tweaks done in FF do visit this link