[HELP] Understanding Performance - Lighting, Foliage and Overdraw.

[No idea in what category this belongs, so i’m posting it here]
I am working on a simple scene that is quite ambitious, with that I mean that my scene only has some foliage and rocks.
The ambitious part is that my landscape is 8kmx8km.

I am running into some performance issues that I just can’t seem to understand as to why the GPU is taking up so much time for rendering. And because of that I am struggling fixing this issue.

I have already optimised A LOT in this scene, by adjusting rendering distances for grass, shadow and enabling Distance Field Shadows.

It would be great if someone who has more knowledge of creating scenes like these to help me out, since this is my very first “open-world” scene.
Also I will keep posting here if I find a way on my own to fix the performance.

Here are some screenshots that explain a lot better than I can do with words.

As you can see the FPS is about 25 when rendering far into the distance.

Shader Complexity isn’t bad, however some assets are rendered in grey squares?

The quad overdraw isn’t bad either.

Quad overdraw and shader complexity is really bad in combination, but why not when viewing them seperately?

GPU Profile console command results, when rendering far away distance.

A more closeup view that has good performance at around 60FPS on average.

GPU Profile view from the close up shot.

My Early Z-Pass settings.