Firefox: When you to restore your previous session from Firefox's start page, it doesn't load all your tabs at once. Extension tabPreLoader alleviates this annoyance.
Firefox's default behaviour can be useful, but if you'd prefer that it load all your tabs when you restore a session, tabPreLoader will do the trick. After you install the add-on, it simply instructs Firefox to load all the reloaded tabs completely. You can also configure how many tabs, in relation to the currently viewed tab, are reloaded upon startup.