Using SharePoint 2010 Processing Page in code

For long operations, one could use the following code in order to display the SharePoint's default processing page.

string

{

      operation.Begin();

      //Your Code

      operation.End(comeBackUrl, Microsoft.SharePoint.Utilities.

}SPRedirectFlags.DoNotEncodeUrl, System.Web.HttpContext.Current, null);

Also Refer: http://peterheibrink.wordpress.com/2009/09/07/splongoperation/ 

comeBackUrl = SPContext.Current.Web.Url.ToString();using (SPLongOperation operation = new SPLongOperation(this.Page))