Printing to file is slow

This is running too slow.  I convert a VB program to C#.  The VB program takes 2 minutes and the C# takes 26 minutes.  I privacy reasons I can 
not send the WriteHistory.  It build a StringBuilder and has a switch statement.  There are 1.7 million records.  
Any ideas on this would be appreciated.


 
arep
 
 

      public static void PrintHistory(SqlDataReader sourceReader, bool b)
      {
         using (StreamWriter sw = new StreamWriter(@"Extract\History.txt", b, Encoding.Default))
         {
            StringBuilder record = new StringBuilder();
            while (sourceReader.Read())
            {
               record = Program.WriteHistory(sourceReader);
               sw.WriteLine("{0}", record);
            }
         }
      }