Starting about 6-8 months ago (whatever version of fire fox browser was at that time) If there is any type of video playing, even a window in a page, it always takes at least 9 or more seconds for the browser to either go to another page, or close. If the page does not have any "Live" video, it will go to another webpage or close very quickly. No new add on's have been installed by the user in over a year.