With WEM Agent 2503 or 2507 installed within Citrix virtual desktop, upon a new ICA session logon, end user may experience an extra 30 sec delay in Windows user logon, compared with the scenario of WEM Agent not installed.
Meanwhile, it is observed from Windows Application Event that, Citrix WEM User Logon Service logs a error event Failed to get user information for CVAD session launch event. Exception: AD query timed out

The 30 sec user session logon delay is introduced by Citrix WEM User Logon Service. Specifically, when Citrix WEM User Logon Service calls Microsoft .NET API: DirectorySearcher.FindOne() to search the logged user in the Active Directory., the .NET API doesn't return within the 30 sec timeout pre-defined by WEM Agent.

Please be kindly note that, when the .NET API takes less than 30 sec to return, 20 sec for example, the error event Failed to get user information for CVAD session launch event. Exception: AD query timed out won't be logged in Windows Application Event. However, end user will experience an extra 20 sec delay upon Windows user logon.

The root cause lies in the slow execution of .NET API: DirectorySearcher.FindOne() in a specific Active Directory environment, which requires a further analysis by Microsoft Support.

From WEM's perspectives, to improve the user experience upon Windows user logon, an enhancement has been made and will be available in the future WEM Agent release.
By the enhancement, the Windows logon duration experienced by end users won't be prolonged by the slow execution of the .NET API: DirectorySearcher.FindOne(), even though the  error event Failed to get user information for CVAD session launch event. Exception: AD query timed out may still be logged in Windows Application.

In case a private build is required for a verification of the enhancement in advance, please create a Citrix Support Case with this Article ID included as a reference.

The article describes a slow user session logon issue related with Citrix WEM User Logon Service