I recently started receiving a lot of emails from Azure AD Connect Health in one of my lab environments indicating that my AAD Connect server was experiencing high CPU usage:
I remembered seeing a tweet from fellow MVP Jeff Guillet about this - He's been tracking this for a while and as it turns out the issue is caused by a buggy Windows update for .NET framework. You can read all about it in the following posts on his The EXPTA {blog}:
- "Fixed" .NET Framework Updates Still Cause High CPU on AAD Connect Servers
- Azure AD Connect version 1.1.880.0 includes many updates
Upgrading to AAD Connect 1.1.880.0 fixed the issue for me.