With the new firefox 13, on start-up it does not reload all of the tabs at once. Theoretically this means firefox loads faster. Since it only needs to load one website when you restore, not all of them. This is a great example of a UX/UI app experience that seems good for users, but is in fact bad. This comes up quite often when optimizing applications, and I have even done this style of optimization in the past. So I'm using this as a case study in why doing this is not good from a UX perspective. The Scenario. I have 8 tabs, and I'm using most of them. Old firefox behaviour. Firefox loads, I go away whilst it loads itself, then loads all 8 tabs. I wait . It takes a while to load - but some stuff can be loaded at the same time, in parallel. If they are fast pages it is pretty much instant, and I can get to work. If they are slow pages, then I have to wait once until they are all loaded. I can go off and do something else until the loads ar