I covered ground by grass and it feels like the game becomes laggy when I walk around grass. Rather frame rate is dropping. Is frame drop is thing in forge?
If you have too many animated objects like grass or tree all clustered together so you can see them all at once, you can quite easily kill your framerate. The same goes for weapons, I have a friend who likes to make armories with 16 of each human weapon and as soon as you walk in your framerate drops to like 10.
Im having the same issue. Seems I need to cut back on the grass and trees a bit.