Thank you @ fLUnKnhaXYU
Indeed does the wheat field look dense enough for a significant drop in fps but the area does not have many other objects; the wheat shapes are instanced via the groundCover system and the drawcalls are low. This makes it that it runs fairly smooth, often even smoother then for example a weed/grass field with a lot of different objects (plants)
The biggest drops take place in the towns where buildings are packed. Especially the amount of objects in and around the buildings result in many drawcalls. Each house has scripted doors, interiors and items spawned. Working with zones in a open world game is problematic and T3D's zones aren't well coded. It causes even drops on certain area's of the map where I am aiming for improvement.
Probably it will take more scripting and loading/unloading hiding/showing assets when they're needed.
ground cover and forests have been fps hitters for me
The default settings for hardware instancing is outdated; most will have much higher detail and therefore it will not work properly. Try to increase and see if it improves. There is a threshold for optimal performance. One can go too high or too low with it.In my case I had to go all the way up to 4000 verts.
// Enables mesh instancing on non-skin meshes that have less that this count of verts.
$pref::TS::maxInstancingVerts = "4000";
once it's working properly you'd want to change that in \game\core\scripts\client\defaults.cs