Having Foliage Optimization Issue in game for VR

Hello people
I am Working in a VR Game and having issue with foliage . Foliage decreasing the FPS to 50 in dens Forest and i need at least 90 fps so Please advise what i can do for that . Any tips and tricks ??

-use low poly meshes
-avoid complex materials
-try to decrease the mesh count (e.g use a good ground texture so that you dont have to use so many grass meshes),…
-try to “block” the view of the player (e.g with a hill, rocks,…)
-use culling
-use good lod’s