How can I optimize shader performance for mobile VR headsets?

<!-- BEGIN COPY / PASTE -->
    // Example of a simple optimized shader for mobile VR
    Shader "Custom/MobileOptimizedShader" {
      Properties {
        _MainTex ("Texture", 2D) = "white" {}
      }
      SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 100

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

          sampler2D _MainTex;
          struct appdata_t {
            float4 vertex : POSITION;
            float2 uv : TEXCOORD0;
          };

          struct v2f {
            float2 uv : TEXCOORD0;
            float4 vertex : SV_POSITION;
          };

          v2f vert (appdata_t v) {
            v2f o;
            o.vertex = UnityObjectToClipPos(v.vertex);
            o.uv = v.uv;
            return o;
          }

          half4 frag (v2f i) : SV_Target {
            half4 col = tex2D(_MainTex, i.uv);
            return col;
          }
          ENDCG
        }
      }
    }
    <!-- END COPY / PASTE -->