Unlit Transparent Color Kills performance

Unity Engine
1

I have made a Unlit Transparent Color shader for my mobile game , but it kills the performance of the gameplay , how can I fix that.

This is my shader :

Shader “Unlit/UnlitAlphaWithFade”
{
Properties
{
_Color (“Color Tint”, Color) = (1,1,1,1)
_MainTex (“Base (RGB) Alpha (A)”, 2D) = “white”
}

Category
{
Lighting Off
ZWrite Off
//ZWrite On // uncomment if you have problems like the sprite disappear in some rotations.
Cull back
Blend SrcAlpha OneMinusSrcAlpha
//AlphaTest Greater 0.001 // uncomment if you have problems like the sprites or 3d text have white quads instead of alpha pixels.
Tags {Queue=Transparent}

SubShader
{

Pass
{
SetTexture [_MainTex]
{
ConstantColor [_Color]
Combine Texture * constant
}
}
}
}
}

2

it’s irrelevant but the documents say capitals:“Cull Back”