If 40-50 FPS is too low for you, I would not touch it. In my mid size tavern I experience sometimes FPS in their mid twenties, that with a 1070Ti and everything cranked up.

That said, they did some changes to the terrain system which should reduce the mesh clutter and drastically improves FPS.

You just have to have the console enabled ("-console" in the command line options). Press F5 when in a heavily modified terrain area and then type "optterrain", which will remove old terrain data, thus improving the performance of the game.