Low FPS on mobile devices

Hello again, I’m doing a mini-game under android, and I ran into some problems.
I already wrote about the problem of the water shader.
The same mesh with the same number of polygons can affect FPS in different ways.
A mesh with a radius of 100

A mesh with a radius of 6

I’m assuming it’s because of the fact your plane is rasterized to fill up the whole screen.

But even that should be trivial. What exactly are you doing with the water shader?