Slow XSLT Performance with Managed Parser

This article was previously published under Q324478
This article has been archived. It is offered "as is" and will no longer be updated.
Extensible Stylesheet Language Transformations (XSLT) style sheets that use the <xsl:key> element may experience slow performance when they are used to transform XML data in .NET applications. You may notice this behavior with large XML data, typically in megabytes.
This problem occurs because the XSLT processor does not handle the <xsl:key> element efficiently. The XslTransform class of the <xsl:key> element is not optimized.
This fix is included in the Microsoft .NET Framework Post-SP2 rollup 6. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
328540 INFO: Post-Service Pack 2 .NET Framework Hotfix Rollup Package 6
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Visual Studio .NET service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
  Date          Time       Version        Size              File Name  ------------------------------------------------------------------------  20-Jun-2002   22:32:30   1.0.3705.291   1,298,432 bytes   System.Xml.dll				

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
This performance degradation occurs even when the XML is loaded in the System.Xml.XPath.XPathDocument data object, which is supposed to be most optimized for XPath and XSLT processing.

Steps to Reproduce the Problem

  1. Start Microsoft Visual Studio .NET, and then create a new Visual C# Console Application.
  2. Include the following namespaces:
    using System.Xml;using System.Xml.Xsl;using System.Xml.XPath;					
  3. Add the following code into the Main() procedure:
        try     {	Console.WriteLine("Starting XSLT Performance Test");	string XslFile = "<Path_to_my_XSLT_File>\\<my_Input_XSLT_with_xsl:key>.xsl";	string XmlFile = "<Path_to_my_Large_XML_File>\\<my_Input_XML>.xml";	DateTime StartTime = DateTime.Now;	XslTransform xslt = new XslTransform();	xslt.Load(XslFile);	XPathDocument xpathdoc = new XPathDocument(XmlFile);	XmlTextWriter writer = new XmlTextWriter("<my_Output_XML>.xml", null);	Console.WriteLine("Transforming XML...");	xslt.Transform(xpathdoc, null, writer);	DateTime EndTime = DateTime.Now;	System.TimeSpan varTS = EndTime - StartTime;	Console.WriteLine("Time taken with System.Xml in seconds: {0}",varTS.TotalSeconds);    }    catch(Exception e)    {	Console.WriteLine("{0}", e.Message);    }					
  4. Compile and then run the application.
  5. Compare the performance with the MSXML 4.0 parser when you transform the same XML data with the same XSLT.


For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
325689 INFO: Performance of XSLT Transformations in the .NET Framework
performance XSLT xsl:key .NET xml xsl

Article ID: 324478 - Last Review: 10/26/2013 17:15:10 - Revision: 3.4

Microsoft .NET Framework Service Pack 1, Microsoft .NET Framework Service Pack 2

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