first of all thanks for the help!
With software RT I get 40ish on Epic but this seems a high cost for whats going on. With Hardware RT I get 8 FPS no matter what I do.
My vegetation is not the problem as it gets best performace when I go deep in it (have a low radius culling) and when I remove it from the whole landscape (using painting in landscape mode) I gain just a few frames.
Based on what you said I did some tests for software RT:
Changed all the white material, which wasnt pure white, to black or colors - no diference
Changed roughness and/or scalability reflections - no diference
For Hardware RT (all epic):
Created another project (car template) and all works fine. Put 192 cars in the scene and used my materials on it, Hardware RT worked even better than just lumen. Migrated all assets from my project to this and there is no difference between software and hardware rt, both lock 60.
All thats left with my basic knowledge of unreal is that maybe I messed up with something regarding the landscape or something is wrong with my project? Thats why I asked about coming from EA, because even setting scalabilty to low with hardware RT I get the same 8 fps