I've seen similar posts, but none that are exactly like the problem I am experiencing. Since updating to FF27 (I'm on a MBP with OSX 10.7), I will go to a page and am unable to scroll down for a short amount of time. Usually it's about 3-5 seconds, and then the 2 finger scroll functionality kicks back in. It's not choppy, just delayed. It seems to happen more on pages with many images on it. I would assume that it had to do with the loading of the images, however, it will happen if I hit the back button to a page that is already cached. I really don't want to switch to a different browser, I've been a dedicated user of Firefox since 2004 and would really like to keep this relationship going : )