SharePoint performance degradation with a large number of unique security scopes in lists

Performance degradation of Microsoft Office SharePoint Server 2007 and SharePoint 2010 with a large number of unique security scope set on folders or documents on a list.

SharePoint 2007:
When more than 1,000 security scopes are created for folders or documents in a list, there’s a significant performance degradation in SharePoint operations that badly affects end users operations(rendering content) as well as SharePoint activities like indexing SharePoint Content.  After the number of unique security scopes exceeds1,000 per list, SharePoint uses a code path that requires additional SQL round trips to analyze the scopes before rendering a view. When there are 1000 or fewer scopes, only one round trip is required. 

SharePoint 2010:
When a greater number of unique security scopes than the value of the List Query Size Threshold (default is 5,000) set to the web application are created for folders or documents in a list, there’s a significant performance degradation in SharePoint operations that badly affects end users operations(rendering content) as well as SharePoint activities like indexing SharePoint Content. After the number of unique security scopes exceeds the value of the List Query Size Threshold, SharePoint uses a code path that requires additional SQL round trips to analyze the scopes before rendering a view.

SharePoint 2007:
Control the number of unique security scopes for a list to be 1,000 or less.

SharePoint 2010:
Control the number of unique security scopes for a list to be less than the value of the List Query Size Threshold.

The links to the related Technet articles are here:

Plan for software boundaries (Office SharePoint Server)
http://technet.microsoft.com/en-us/library/cc262787(office.12).aspx (http://technet.microsoft.com/en-us/library/cc262787(office.12).aspx)

Plan for software boundaries (Windows SharePoint Services)
http://technet.microsoft.com/en-us/library/cc287790(office.12).aspx (http://technet.microsoft.com/en-us/library/cc287790(office.12).aspx)

SharePoint Server 2010 capacity management: Software boundaries and limits
http://technet.microsoft.com/en-us/library/cc262787.aspx (http://technet.microsoft.com/en-us/library/cc262787.aspx)

Understand permissions and permission levels (Office SharePoint Server)
http://technet.microsoft.com/en-us/library/cc262118(office.12).aspx (http://technet.microsoft.com/en-us/library/cc262118(office.12).aspx)

Understand permissions and permission levels (Windows SharePoint Services)
http://technet.microsoft.com/en-us/library/cc287792(office.12).aspx (http://technet.microsoft.com/en-us/library/cc287792(office.12).aspx)

Understand permissions and permission levels (Project Server)
http://technet.microsoft.com/en-us/library/cc197535(office.12).aspx (http://technet.microsoft.com/en-us/library/cc197535(office.12).aspx)

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