unity showing download file delay

 WebClient client;

public void DownloadFile() { client = new WebClient();

     client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
     client.DownloadFileCompleted += new System.ComponentModel.AsyncCompletedEventHandler( DownloadFileCompleted );
         client.DownloadFileAsync (new Uri(url), getPath() + "DEMO.xml");
 }
 void DownloadFileCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
 {
     if (e.Error == null)
     {
         Debug.Log ("Completed");
     } else
         Debug.Log (e.Error.ToString ());
 }
     void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
 {
 }

     private string getPath(){
             #if UNITY_EDITOR
             return Application.dataPath + "/Resources/";
             #elif UNITY_ANDROID
             return Application.persistentDataPath + "/Resources/";
             #elif UNITY_IPHONE
             return GetiPhoneDocumentsPath()+"/";
             #else
             return Application.dataPath +"/";
             #endif
             }