The March 2016 update (4.13) will be deployed on Tuesday, March 8th. The 4.13 update provides significant performance improvements for the My Groups, My Classes and My Announcements apps. 

The update is planned for 5:00 pm local time. During the update your sites will be unavailable for a few minutes.

If you do not have a SharePoint 2013 Portal (or My Site) this hotfix will not be applied.

As this update affects only performance only subscribers of the Technical Notices list have been notified.