FIX: High CPU usage when you run a .NET Framework 3.5.1-based application on Windows 7 SP1 or Windows Server 2008 R2 SP1

Applies to: .NET Framework 3.5.1Windows 7 Service Pack 1Windows Server 2008 R2 Service Pack 1

Symptoms


You encounter high CPU usage when you run a .NET Framework 3.5.1 or Microsoft SharePoint 2010-based application on servers that contain more than 16 processors and the processor load cannot be attributed to application workload. 

Note The .NET Framework 3.5.1 was not optimized for large multiprocessor servers. The following environment variable may reduce some CPU load. However, we recommend that you do not apply these settings until the application performance characteristics are fully understood and until all application workloads are fully accounted for.
Environment VariableDescriptionRecommended Setting
COMPLUS_SpinLimitProcCapSets how many processors to use for certain Runtime calculations. Default value is the actual processor count.A value from 2 to 8.

Resolution


To resolve this issue, download and apply the hotfix from the following link.

Hotfix information

A supported hotfix is 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.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.



Prerequisites

To apply this hotfix, you must have Microsoft .NET Framework 3.5.1 installed.

Restart requirement

You have to restart the computer after you apply this hotfix if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this hotfix.

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.