Logging

Since 2010 the Office applications will write information to the Windows Application Log.
This information can be seen using the Event Viewer.
Each entry includes a Boot Time value indicating the amount of time it took for the add-in to be loaded.
Any add-ins that are loaded after the Office application has already started also get added to the Application Log.
This might only apply to Outlook

link - learn.microsoft.com/en-us/outlook/troubleshoot/performance/event-log-entries-for-add-in-load-time