how to find all the visible UI elements on the screen ?

very sorry for my bad English
am making app with simple canvas using scroll rect and layout group
the user should be able to add raw images to the layout group
so at least the app should work fast with 100 raw image in the layout group
what will be visible on the screen is not more then 3 or 4 raw images at time
the user have to scroll to see the other raw images
but the problem is when i add 100 image or 50 or any big number the app became very slow
what i want to do is to get all the visible UI elements and set them active and disable all the other elements this should help me to get the app faster
any ideas how to achieve this ?
thanks for your help

Hello

You should read this manual and look for some youtube tutoria to know how to use it correctly

Good luck!
Bye!