I installed a set of whatever Windows Updates were waiting to be installed on a Server 2012 R2 Hypervisor host running 5 virtual machines, and installed all available updates on the virtual machines on April 15. This server backups up with full backup job at 7pm once a day - data size is about 1.43 tb all included. Backup media are two 6tb Seagate USB 3 drives connected on a USB 3 port, switched out daily. Prior to the install of the updates on April 15, the backups would typically complete by 2am the following morning. After installing the set of updates, the backups now run until at least 11 am the following morning, sometimes finishing after noon. I install Important, Recommended, and Optional updates. Prior to the April 15 update session, the last round of updates were installed 2/19. Of the 50 updates, 42 installed successfully. I do not see any of the 8 'Failed' updates on the available list of updates currently listed (all say Optional). I assume the 'Failed' status of the 8 that did not install indicate they were not needed when it got to the point of the installation. Server is set to 'Download and let me choose whether to install', so they will be already downloaded when I get the time to install them. Likely some were downloaded sometime early since 2/19, then superceded by newer updates and were not required.
Regardless, one or more of the 42 installed updates has pushed this server from less than 7 hours to over 16 hours regularly to complete the full server backup.
Anybody? Bueller? Bueller?