I am using Firefox now for almost 7 years as my main browser (Chrome still installed for some pages not properly working in other Browser). But the number you are mentioning here are just not true with current versions of both browsers. Overall I agree that FF still has potential to improve it’s rendering performance (like every other browser). But as an end user it’s not noticeable anymore. Quite the opposite is the case for me since FF always used way less resources than Chrome on my notebook.