Microsoft KB Archive/919490

= Programs that throw many exceptions run significantly slower on a Windows XP Service Pack 2 (SP2)-based computer =

Article ID: 919490

Article Last Modified on 8/29/2007

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APPLIES TO

 Microsoft Windows XP Service Pack 2, when used with:  Microsoft Windows XP Professional

 Microsoft Windows XP Home Edition 

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SYMPTOMS
When you run programs that throw many exceptions, you may notice that these programs run significantly slower on a Microsoft Windows XP Service Pack 2 (SP2)-based computer.



CAUSE
This problem occurs because of the Data Execution Prevention (DEP) feature of Windows XP. There is an option in Windows XP to disable the DEP checks to improve program performance. However, if you use this option, it does not disable all the new exception-handling security checks that DEP performs.



Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note This hotfix will disable the exception-handling security checks when DEP is disabled.

Prerequisites
No prerequisites are required.

Restart requirement
You must restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later file attributes) 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 item in Control Panel.

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STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

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MORE INFORMATION
Generally, exception handling is very fast and takes less than 10 milliseconds. Therefore, a program that throws few exceptions will not demonstrate slower performance. However, a large program that throws thousands of exceptions in a short time may demonstrate significantly slower performance.

To determine whether a program throws a sufficient number of exceptions to slow performance, you can use a profiling or debugging tool such as:
 * Dependency Walker
 * Microsoft Visual Studio
 * Microsoft Debugging Tools for Windows

For more information about the DEP feature, click the following article number to view the article in the Microsoft Knowledge Base:

875352 A detailed description of the Data Execution Prevention (DEP) feature in Windows XP Service Pack 2, Windows XP Tablet PC Edition 2005, and Windows Server 2003

For more information about standard terminology that is used to describe Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Keywords: kbwinxpsp2fix kbbug kbfix kbhotfixserver kbqfe kbpubtypekc KB919490

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