That's not a problem I recall encountering in the days of Firefox 2.0.
I guess it's too much to ask companies not to implement websites that leak memory.
2) I'd prefer software just, you know, not be bad. Safari, for all its problems, demonstrates that there's nothing inherent in a modern desktop web browser that requires it to be grossly inconsiderate of your system resources.
I remember these days clearly because Firefox 1 was very fast and it displaced Mozilla (what was later called "Mozilla Suite") as the main browser for the Mozilla Foundation exactly because of that performance benefit. However Firefox 2 not only ended up becoming much slower but Mozilla Suite actually became faster and ended up being faster than Firefox despite providing not only a browser, but also a mail client, news client, WYSIWYG editor, IRC client, etc - ie an integrated "internet client".
At the time i liked Mozilla more than Firefox so i was bitter about it and how it was eventually abandoned by Mozilla Foundation (it became Seamonkey, sure, but that is another story).
IE6, on the other hand, would be usable in less than 10 seconds from launch. Granted, it probably got preloaded by Windows, but even Windows took less than 5 minutes.