How to increse the performance ? While Writting data into text file

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C#

Hi,
I have one Sql Table which is having two columns Rowid – int, XMLRecord – XML which contains 1000000 records in it. I have to read that record & write that in to text file.
I have written program to do that but it is taking near about 25minute to do that how can I increase the performance of this process
I have methods like this

ReadXML()
{
  Sql XML to get data from Sql table
  XMLReader to read node of xml 
  This is returning Entity object
}

WriteXML (Entity object)
{
  Here I am using some more variable & objects
  I am using some looping to get data from Entity object
  StreamWritter to write into file
}

In this case ReadXML () method is taking only 3 minutes and WriteXML (Entity object) is taking more time.

How can I increase performance of this program? Which care should I take while using loop, StreamWritter and in loop I am creating some local object it is necessary to destroy that . Which method should be the best to dispose those objects?
Please assist me….

-Dattatrya Moin