2d game performance is bad in mobile, but giving 80 to 130 fps in pc, its physics game, help plz

I made a game in unity4.3 built in 2d ,game has lots of 2d rocks with rigidbody and polygon colliders,
the game is working smooth in pc and mobile with upto 1 gb ram, but its not working smooth with my mobile i have but its playing all heavy games from playstore, i dont no what should i do,

i am using built in diffuse shader in graphics setting.
…quality setting is faster

need help!

i found a shader from madfinger it reduce my draw calls,

// Unlit shader. Simplest possible textured shader.
// - SUPPORTS lightmap
// - no lighting
// - no per-material color

Shader "MADFINGER/Environment/Unlit (Supports Lightmap)" {
Properties {
	_MainTex ("Base (RGB)", 2D) = "white" {}
	_Color ("HACK: temporary to fix lightmap bouncing light (will be fixed in RC1)", Color) = (1,1,1,1)
}

SubShader {
	Tags { "RenderType"="Opaque" }
	LOD 100
	
	// Non-lightmapped
	Pass {
		Tags { "LightMode" = "Vertex" }
		Lighting Off
		SetTexture [_MainTex] { combine texture } 
	}
	
	// Lightmapped, encoded as dLDR
	Pass {
		Tags { "LightMode" = "VertexLM" }

		Lighting Off
		BindChannels {
			Bind "Vertex", vertex
			Bind "texcoord1", texcoord0 // lightmap uses 2nd uv
			Bind "texcoord", texcoord1 // main uses 1st uv
		}
		
		SetTexture [unity_Lightmap] {
			matrix [unity_LightmapMatrix]
			combine texture
		}
		SetTexture [_MainTex] {
			combine texture * previous DOUBLE, texture * primary
		}
	}
	
	// Lightmapped, encoded as RGBM
	Pass {
		Tags { "LightMode" = "VertexLMRGBM" }
		
		Lighting Off
		BindChannels {
			Bind "Vertex", vertex
			Bind "texcoord1", texcoord0 // lightmap uses 2nd uv
			Bind "texcoord", texcoord1 // main uses 1st uv
		}
		
		SetTexture [unity_Lightmap] {
			matrix [unity_LightmapMatrix]
			combine texture * texture alpha DOUBLE
		}
		SetTexture [_MainTex] {
			combine texture * previous QUAD, texture * primary
		}
	}	
	

}
}

Diffuse shader is different for mobile and desktop. You can switch it by going on your material, changing shader from diffuse to
mobile → diffuse.

if you already have mobile shader chosen, you should make your texture smaller ex. 200x200 (inspector->max size) or with image editing software.

There are multiple other things you should do to optimize your game and you can find those googling your problem.