Ok will do thank you 
This definitely seems related to your assets as the majority of the memory is going to FoliageInstancedStaticMeshComponent, Texture2D and other things related to rendering. As this isn’t a bug with the engine, would it be possible for you to make another post for your specific issue in our Rendering section?
This is partially so we don’t derail this particular thread, but also because Rendering memory usages aren’t something I’m very familiar with so you would likely get more help there.
For anyone with the same issues my new post is here: Assistance with HIgh memory Usage & Light Building - World Creation - Unreal Engine Forums