These concepts do not go together.
Yea I knew once the brick count exceeded 20K I wouldn't be able to get as far as I planned, however I have come up with a different approach to building it with a much lower brick count and a lot less lag. So far I am just using the picture above as a proof of concept.
A) Way too many bricks for one area. I blame your trees
B) Terrain is a bit too flat. Needs more hills
C) Your using the grass emitter? ..why?
A) answered above^
B) yea I will definitely work on multilevel terrain that is more than a few plates, this was just something quick to test and see how it looked.
C) I was way too lazy today to build the grass