Slow initial startup. What to do?

Hi everyone,

I build an app which main Page is a TabbedPage which contains 6 - 7 "Sub"Pages. Every "Sub"Page is a ContentPage besides of two which are a CarouselPage and a MasterDetailPage.

My problem now is that when the app starts for the first time (and every other time when not loaded from memory) the duration till the first Page is shown is something between 5-10 seconds. So the user is only seeing a black screen with the ActionBar for this duration.

Is this Forms related or Xamarin in general and what can I do to improve startup time?