Netscape and memory are amazing nearby

I read the DileSoft topic about its transition to Netscape Navigator and decided to try it too, and at the same time check whether it really is more economical with RAM. I was not very interested in the design because I usually place the address and search lines to the right of the main menu of the program and I don’t actually notice the differences. From the pleasant little things - I found out that you can leave a cross close only on the active window without installing tabmixplus.

So, the comparison conditions:
OS - Windows XP SP2
Browser Versions:
FF 2.0.0.8
NN 9.0.0.1
Images are disabled and the following extensions are installed:
Favicize tab
ImgLikeOpera (through which pictures are turned off)
FlashBlock (I do not like flash banners, and you?)

Testing was modest, because NN simply tore FF like a hot dog. It was not interesting to continue further.
When loading three pages - Google Reader , Gmail and New FF ate 41 megabytes, and NN only 22. I tried to open more tabs with Habr, BOR and Exler's blog - FF finished the 98th megabyte, while NN huddled at 42x.
')
One thing is surprising - how did they manage it? Why couldn't the Mozilla developers have done the same before? What's the catch?
I have already made my choice in favor of NN. Waiting for patches in FF?

PS Get NN !