When I open Firefox for the first time when I turn on my computer, my main page apparently opens twice because it lags and I can see the website twice in my history. It then proceeds to do this with any link or website I go to. The website opens and looks sluggish and then I look in my "back button" history and the website is there twice. It makes Firefox operate slowly and it's a nuisance. I've tried reinstalling but that doesn't seem to work.