Did you know that access to properties in the app object is more than 1000 times slower than accessing the same property in a module?
My testing shows that accessing app calls internally a function App which calls a function GetAppObject. Both spend a lot of CPU time for stack checking, cast checking and background tasks.
To move methods and properties from app to a module, you should create a module in your project and save the project in the text format. There you can simply copy & paste all your methods and properties in big chunks.
Here my test project:
Also I made a feedback report: case 16764. Please sign on if that is of interest for you.