How come when I try my scene on the tablet takes a little while to load. Is there any instruction to load the various objects in the scene? I have a very simple ground enemies with a generator of some element of decoration but it takes those 15/20 second to load. Solutions are there? thanks 
Have you used profiler to check out what is actually causing the long load times?
no I did not know there was something to do. How should I do?
Which format are the textures and their size? they are compressed or uncompressed?
It was the land that gave me problems I solved it by putting a plan. It 's normal that the ground can give these problems being small in size?
Same problem of slow loading…
I solved it by resizing the ground and using bump instead of the details with a brush
Don’t use built-in Unity terrain for Android (if you’ve a big terrain), create a mesh and optimize it, will improve performance a lot.