I have simply application written in c#, with sqlite database. I realized that it's not working fast on my phone. I'm pretty sure that problem is linked with functionality of pressed bulit-in back button. When I repeat several time this process:
Open new page -> return to previous page by back button, the application starting slows down.
When I added my own back button only to test, everything works fine.
I base mostly on this article: http://www.wintellect.com/devcenter/jprosise/handling-the-back-button-in-windows-10-uwp-apps
Open new page -> return to previous page by back button, the application starting slows down.
After looking into your project, I found out the problem: You are registering SystemNavigationManager.GetForCurrentView().BackRequested +=OnBackRequested on every page. SystemNavigationManager.GetForCurrentView().BackRequested is an application scope event. It won't dispose the eventhandler when you are navigating between pages. You only need to register it once in your whole application.
So, to fix the problem, you can comment out all the BackRequested event registration of your pages's code-behind and keep only the one in your App.xaml.cs.
For example: in ProductsPage.xaml.cs comment out or delete following lines:
//SystemNavigationManager.GetForCurrentView().BackRequested += (s, e) =>
//{
// // TODO: Go back to the previous page
// Frame.Navigate(typeof(main1));
//};