Go to “about: config” enter “newtab” in the search field and change “browser.newtabpage.enabled” to false … and the advertisement is gone. Mozilla adds will be introduced on the page when you want to add a new tab.
The nine rectangles with links to websites you have visited, a feature copied from Opera (speed dial) for a couple of years ago, to be filled with paid advertisements.
Browsers should never have Commercials. That is up to the websites to have. Internet Explorer had this for long time and also many Commercial extensions does that already too. When I visit some of my clients complaining about browsing speed. The very first thing I do, is to get rid of browser extensions that is made for you to get overdose of Banners everywhere. One of those Commercial extensions I have seen, changed Google search site to their own so that even you thought you were searching using Google, it was something else.
The best thing now is to go for other browsers than Firefox. This is such negative news shock! Why Mozilla??? Distrita now would recommend anyone to Choose Google Chrome, Opera, Safari or OWB.