Efficiently Delete / Purge All Items from a SharePoint List

private static
StringBuilder BuildBatchDeleteCommand(SPList spList)

    {

        
StringBuilder sbDelete = new StringBuilder();

   
sbDelete.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?><Batch>");

      
string command = "<Method><SetList Scope=\"Request\">" + spList.ID + 

"</SetList><SetVar Name=\"ID\">{0}</SetVar><SetVar Name=\"Cmd\">Delete</SetVar></Method>";

        foreach (SPListItem item in spList.Items)

        {

           sbDelete.Append(string.Format(command, item.ID.ToString()));

       }

       sbDelete.Append("</Batch>");

       return sbDelete;

  }