Ever since the update to Firefox 13, I have been experiencing the worst lag I've ever known on a modern computer. There is lag when I'm typing, such as now as I type this (I just wrote that last sentence with nothing happening, only for it to show up in the text box a few seconds later). There is lag with the loading of web pages, with the changing of the cursor icon as you hover over a link, with videos, with everything. When I first open Firefox, it runs perfectly for all of about 5 minutes. I don't have to do anything, the lag will start to occur. In small intervals at first, but with increasing frequency and longer pauses as time goes on. I can't have Firefox open for more than 20 minutes before I'm driven crazy by the lag and I have to restart it. Presently, Firefox is completely unusable. I cannot understand why this update was released. I was not experiencing any of these problems with lag prior to the update to Firefox 13, which I allowed because updates are generally supposed to be improvements, right? I tried doing a clean uninstall, removing all files and folders associated with Firefox, doing a registry clean to remove all straggling registry keys left behind by the uninstall, then reinstalling Firefox 13. I thought for sure the problem would go away at this point because this is an absolutely clean install, right? No plugins, no nothing. Just Firefox. But, no. The lag continues, and it's making me crazy. I'll use Google Chrome or some such for now. But I would like to one day be able to return to Firefox, since it is the only browser ever created that I actually like.