Firefox is a PIG on memory

[Matt Patterson]

I have noticed that if I leave firefox open for a long time (week or 
more) that the memory usage on my machine just steadily climbs (swap and 
memory used). Even if there is only one firefox window open, the instant 
I close that window I can watch my memory usage drop 300mb or more. I 
like leaving many windows open (several per desktop with several tabs 
each) because that is how I organize my various parrallel tasks. A way 
to make firefox clean up after itself would be great.

Any ideas?

Matt