This has never before happened to me. After installing the new OS X update today, Safari started lagging so much, especially while scrolling, that it is literally unusable. I have disabled all the extensions to isolate the problem to Safari itself. I have made a video, hope my ordeal is clear from it: I made a comparison with Firefox to make it clear that it's not because of the internet connection or any "external" factor. The computer sometimes even completely freezes for a couple of minutes when Safari is in the foreground, it happened right when I was about to write this post. Des anyone have the same problem?