@theluthier I am using weight painting to control the Density of the Grass (not the Scale) here:

In the Node before (left of) that, I ‘multiply’ that with where grass should be (e.g.: not inside the house) to further reduce the amount of Instances, so that, if I remove the Scaling, we get:
As far as I can tell, the lagging is a combination of the Dynamic Painting, the amount of Instances and the Attribute Mix Node, but I am not sure which factor is most important….
Anyway, it would still need a lot more grass to fill up the Camera FOV, so I’m not sure if this will be useful…