Oh, it is definitively my surfing habits.
But, that has no connection with the fact that leaving FF with open tabs alone for a week nearly doubles its memory footprint.
That also has no connection with the fact that on my 3GB RAM + 3GB swap Windoze XP machine Chrome constantly thrashes, and my memory usage without open browsers is less than 1 gig total.
Now, I do realise than my habit of running multiple browsers with around 50 tabs open is not a socially accepted behaviour, but constantly adding features without addressing old issues seems futile. FF 3.0 did show a big improvement in memory management, and even bigger in stability. Yet, I am still seeing issues from years ago with plugins and memory.
Considering my browsing habits, I still haven't found a bookmark / tab tool that saves context - history and opened child tabs, let alone the content of the tab as it was when saved. With something like that, I probably would have no need for 50 tabs, and would stop complaining. One can dream...