I Think that is a war or a race between browsers, to compete !
And its good, we will has a little better browsers ! ;-)
The race Chrome vs Firefox, its very visible in the last times:
Chome is scaling in the ranking
But the Mozilla has released Firefox 4, a new version, very most speed, very clean, wide screen and functional !
The organization of the tabs (panorama) as so fantastic ! :-D
Firefox is so a one of the addons take firefox slower !
But the rest of the addons is very, very fantastic ... and i dont discovered any similar in Chrome !
I love firefox, and i dont think to change to Chrome, im so mutch good served with Firefox ! lool