Since updating, the cache often no longer clears properly. I had an issue where old images would not refresh, even after manually clearing the cache (I have browser cache disabled off via the firebug setting btw). Other browsers showed the new images after one or two page refreshes. Firefox took many refreshes, opens/closes, and even then did not show the new images until I checked later. I've also seen a similar issue with the offline cache. We have some pages at work that store as offline, and firefox does detect the change in the cache manifest and claims to have 'made the update', but still shows the old version of the offline page, even after refresh and browser restart. I have to manually remove the offline data for this to work. Other browsers show the new page after a simple refresh.