firefox 3 - new memory usage record - ouch!

I love firefox 3 - I have been using it now since the delicious plugin got released (as per my post here). But this morning after the computer rebooted following Microsoft’s Vista patches last night, restoring my session ended up creating a monster.. Firefox 3 chewed through nearly 1.5GB of memory.. ouch! Thanksfully a reboot and starting a new session solved it. I wonder what caused it