You experience slow performance and high CPU usage (reaches to 100%) issue in a machine that runs Azure Active Directory (Azure AD) Connect Health for Sync monitoring agent. In task manger, you notice that the process MIcrosoft.Online.Reporting.MonitoringAgent.Startup uses the high CPU usage.
The issue is not limited to specific Azure AD Connect Health versions and operating system versions.
This issue occurs because June 2018 update of NET framework 4.7.2 is installed in the machine, and Azure AD Connect Health for Sync monitoring agent does not fully support this update.
The following .NET framework update would cause the high CPU issue of monitoring agent:
.Net framework update
Windows Server 2008
Windows Server 2008 R2
Windows Server 2012
Windows Server 2012 R2
For Connect Health for AD DS and AD FS:
To resolve this issue, install the Azure AD Connect Health Agent, version 188.8.131.52 that is released on July 2018. It can be downloaded from Connect Health public documentation.
For Azure AD Connect:
A new version of the Azure AD Connect will be released soon. It will contain a fix for this high CPU usage issue. We will update this article when the new version of the Azure AD Connect is available.