Unity UI 700 UI inside the canvas

Hello,

I am developing a 2D game for Mobile, in my scene I have 500 UI elements, in the old cell phones the game goes very slow, the phone gets very hot, there are some ways to increase the performance of UIs?

Edit:
Profiler Result:
Fps: 48
CPU ms: 18
GPU ms: 17

 

Divide your scene up using subcanvases.

Any time one UI element changes, all of your vertex buffers have to be recalculated, which includes comparing every element in the canvas for overlap with every other element. If you divide your one canvas with 500 elements into 20 canvas with 25 elements each, this processing will be much faster, and only the canvas that have an element that changed will have to be rebuilt each frame.

 

Optimizing Unity UI
https://unity3d.com/de/learn/tutorials/topics/best-practices

 

In my scene I have these elements:

1) All background UI images
2) ScrollRectNum1 with a mask, inside I have 20 UI images (card) with 12 other UI images
3) ScrollRectNum2 with a mask, inside I have 60 UI images (card) with 12 other UI images inside

Do I have to put the sub-Canvas on each card? Or should I put the sub-Canvas in the groups 1-2 and 3 above?

 

help pls