With bug 920623 the transition in the settings apps are coming back, but currently in settings when a panel is opened all subpanels are loaded at the same time. It ends up beeing very heavy and prevent the animation happens the first time it is opened and it also ends up consuming unuseful resources since some panels may never be used. So changing the current panel loading logic to load one panel at a time and don't load the subpanels until the user try to access it should make the situation much better.

Most panels put the logic of sub panels in one script file. We should also separate the scripts and lazy load/execute them.

I'll take this one. Seems like it may be a non-trivial amount of work to split up all of the panels, so I may end up turning this into a meta bug and opening a bug for each panel.

Remove whiteboard keyword for user story since we no longer use this one for settings app refactoring. Please refer to bug 969265 for more detail

Settings is being handled differently now, so we should be good.