Why does Firefox require 1 gigabyte of memory to run with only one window open?

Because it is not a stable browser. I use firefox only watching videos because of my video card issues. Firefox dead on September 2, 2008... You can look at solutions offered by mozilla team; they all say "remove firefox and install it again" :-) This is fun. If you look for a browser to use every day, it should not be firefox. Take care.