Reading large text file of 600 mb.When I execute this code computer hangs after 10 mins but works fine for 100mb file

public static void BulkUpdate(string col, System.IO.StreamReader sr, string tableName)
       {
           ConnStr = ConfigurationSettings.AppSettings["ConnStrAffiliate"].Trim();
           SqlConnection myConn = DAO.fetchConnection();
           //string line = sr.ReadLine();
           string[] value = col.Split(new char[] { '\t' }, StringSplitOptions.RemoveEmptyEntries);
           DataTable dt = new DataTable();
           DataRow row;
           foreach (string dc in value)
           {
               dt.Columns.Add(new DataColumn(dc, typeof(string)));
           }

           while (!sr.EndOfStream)
           {
               value = sr.ReadLine().Split(new char[] { '\t' });
               List<string> valueList = value.ToList();
               valueList.RemoveAt(valueList.Count - 1);
               value = valueList.ToArray();
               if (value.Length == dt.Columns.Count)
               {
                   row = dt.NewRow();
                   row.ItemArray = value;
                   dt.Rows.Add(row);
               }
           }
           SqlBulkCopy bc = new SqlBulkCopy(ConnStr, SqlBulkCopyOptions.TableLock);
           bc.DestinationTableName = tableName;
           bc.BatchSize = dt.Rows.Count;
           bc.WriteToServer(dt);
           bc.Close();
       }