Question related to optimization in unity3d


I am new to unity, I am working on a 2d game. I have created a background that scrolls infinitely over time. For that I have created a plane as a game object and assign it a material and to that material I have assigned a texture. now I change offset of the texture every frame through a script. It looks fine when the game starts but if I let game running for about 30 mins or so it starts showing waves in the background here is my code

public class BackgroundManager : MonoBehaviour {
	public int materialIndex = 0;
    public Vector2 uvAnimationRate = new Vector2( 0.0f, 1.0f );
    public string textureName = "_MainTex";
	public float speed = 0.5f;
	Vector2 uvOffset =;
	// Use this for initialization
	void Start () {

	// Update is called once per frame
	void Update () {
		uvOffset -= ( uvAnimationRate * Time.deltaTime * speed) ;
        if( renderer.enabled )
            renderer.materials[ materialIndex ].SetTextureOffset( textureName, uvOffset );


An Edit: I will be deploying this code to android/ios devices.
please help

is it possible to use 2 planes and swap them with zeroing positions each loop?