I recently encountered an issue with a Microsoft Dynamics SL customer reporting slow performance from their Windows 7 workstations just after a Patch Tuesday. The application was configured to use Windows Authentication and the users were able to launch Dynamics SL but the login process never completed.
To make it more interesting, the users running Windows XP could launch the Dynamics SL application without issue and had no performance issues. Rolling back the patches applied from Microsoft Update allowed the users on Windows 7 workstations to finally login but the login process took close to 5 minutes. Screen performance was beyond unacceptable. After several hours of troubleshooting we ruled out Dynamics SL as the cause of the problem.
The IT Manager was able to determine the issue was related to LLMNR (protocol that allows both IPv6/4 computers to perform name resolution for the NetBIOS names of the other computers without requiring a DNS server). LLMNR was introduced with Windows Vista and is enable by default on Windows 7 and Server 2008.
The resolution to the performance issue is to disable the LLMNR protocol. Below are links to articles that explain the issue in more detail and provide the steps to turn off LLMNR.
https://ttcshelbyville.wordpress.com/2012/02/13/slow-sql-connection-windows-7/
http://technet.microsoft.com/en-us/library/bb878128.aspx
If you are an existing Customer or interested in becoming a Customer and have questions or need assistance please contact us at acumaticasupport@swktech.com.
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