The universal UI uses the lazy loading concept. This has the benefit of not having to load the whole application upon login. This makes the UI feel a lot faster than its predecessors.
However upon opening a screen it will load all the required components for this screen. This sometimes makes loading/opening of a screen feel kind of slow.
I personally think that having a kind of hybrid form of lazy loading and loading the whole application would be perfect. It would be super usefully to fully load the screens, that a specific user opens most often, upon loading (login) the application (top 5 for example).
IAM can be used to determine the top 5 screens which have to be preloaded.