Check out apptim.com. It is specifically for testing client side performance for native mobile apps (Android and iOS) and it is also free to use.
Here is a good article that explains more about the tool and what there iss to know about it before getting started: https://blog.apptim.com/mobile-performance-testing/
I believe the UI has a certain hierarchy and normally object hierarchy has ordered structure (like XML). That means that when you add an element you don't just add it to a random place but to a specific place. Usually it is either the top or the bottom of outer container.
So assume you have the structure like this: