Tutorials/resources for building performant worlds with extremely long sight lines
I am new to environment design - I can C++ and have made my game mechanics, but I have never designed anything visual. I am creating a game with very long sight lines. The max will be about 5.6 km (diagonal of a 4x4km world). I have found plenty of tutorials for building "pretty" worlds but am struggling to find things related to performance especially when it comes to such long distances. For example if I am looking at grass/tree assets are there specific things I should be looking for that would help with performance in this respect?
More specifically for my use case, the player cannot move around the world - think of it like a turret game but with really long sight lines. The turret can spawn at different locations on the level loading, but that location is fixed and can only be changed by a level reload. Given this fixed reference, are there any performance tricks that I can use with regard to assets? For example using 2D bushes that are always turned to face the player like older games used to do (I don't know if this is viable it's just the first thing that came to mind).