Sometimes, Windows might start correctly but might take an unusually long time to do so. Such a problems can be difficult to troubleshoot, because there’s no straightforward way to monitor processes while Windows is starting. To help administrators identify the source of startup performance problems, and to automatically fix some problems, Windows Vista includes Windows Boot Performance Diagnostics.
You can use the Group Policy settings to manage Windows Boot Performance Diagnostics in an Active Directory environment. In the Computer Configuration\Administrative Templates\System\Troubleshooting and Diagnostics\Windows Boot Performance Diagnostics node, edit the Configure Scenario Execution Level policy. When this policy is enabled, you can choose from the following two settings:
Detection And Troubleshooting Only Windows Boot Performance Diagnostics will identify startup performance problems and will add an event to the Event Log, allowing administrators to detect the problem and manually troubleshoot it. Windows Boot Performance Diagnostics will not attempt to fix the problem, however.
Detection, Troubleshooting, And Resolution Windows Boot Performance Diagnostics will identify startup performance problems and automatically take steps to attempt to alleviate the problems.
If you disable the setting, Windows Boot Performance Diagnostics will neither identify nor attempt to resolve startup performance problems. For Windows Boot Performance Diagnostics to function, the Diagnostic Policy Service must be running.
Settings for Windows Shutdown Performance Diagnostics, which function similarly to the Windows Boot Performance Diagnostics, are located in the Computer Configuration\Administrative Templates\System\Troubleshooting And Diagnostics\Windows Shutdown Performance Diagnostics node.
From the Microsoft Press book Windows Vista Resource Kit, Second Edition.