People have been noticing that Microsoft’s recent April 9th security update is causing some problems with a few antivirus vendors like Sophos, Avira, Avast, McAfee and some others.
Microsoft has stated that the the Security Update is causing end user computers to have very slow startup times bad performance and be unresponsive and even causing systems to fail to boot.
“Microsoft is working on a resolution and will provide an update in an upcoming release,” according to Microsoft.
Currently the root cause of the issue by the April 9th security patch is unclear. But both McAfee and Avast suggest that the problems are tied to the change Microsoft made within the Windows Client-Server Runtime Subsystem (csrss.exe). This CSRSS process is a vital part of Windows and is responsible for many windows functions.
Currently there is no fix for this issue.