How can I optimize shader performance for complex lighting in AR environments?

<!-- BEGIN COPY / PASTE -->
    // Example: Optimize shader with LOD and efficient lighting
    Shader "Custom/OptimizedLightingShader" {
      SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200

        Pass {
          CGPROGRAM
          #pragma vertex vert
          #pragma fragment frag
          #include "UnityCG.cginc"

          struct appdata {
            float4 vertex : POSITION;
            float3 normal : NORMAL;
          };

          struct v2f {
            float4 pos : SV_POSITION;
            float3 normal : TEXCOORD0;
          };

          v2f vert (appdata v) {
            v2f o;
            o.pos = UnityObjectToClipPos(v.vertex);
            o.normal = UnityObjectToWorldNormal(v.normal);
            return o;
          }

          half4 frag (v2f i) : SV_Target {
            half3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
            half diff = max(0, dot(i.normal, lightDir));
            return half4(diff, diff, diff, 1.0);
          }
          ENDCG
        }
      }
    }
    <!-- END COPY / PASTE -->