I suspect a lot of it is just a premptive cache. My daily runner laptop is a 2009 Core 2 Duo with 4GB of RAM and Firefox only uses about 1.5GB max when there is about 20 tabs open. It tries to fit in with whatever system it is running on.

Back in 2006 I remember using Firefox on a WinXP system with only 128MB of RAM, while the start up time was dreadful, once it had finally mapped out the memory/swapped all the right parts to the HDD it was surprisingly snappy. I would guess it is still doing something like that now only it doesn't have to swap it out anywhere.

There is Javascript interpreter, caches and other memory consuming things ;)

Although I'd like to read and respond to the reply made by Emre_Ozkan, it is unfortunately [flagged] and [dead]

Quite disappointing whenever I see this type of...of censorship, would this be considered??? I am sure there are many interesting perspectives and this is not the first occurrence of burying comments and/or responses that I have observed as a longtime lurker