Terrain.heightmapMaximumLOD

Description

Lets you essentially lower the heightmap resolution used for rendering.

This can be used on low end cards to never display the highest lod terrain. A value of 0 means always showing highest detail. A value of 1 means the triangle count will be reduced to 1/4th. The heightmap resolution will be halved for width and height.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        Terrain.activeTerrain.heightmapMaximumLOD = 1;
    }
}