I wonder on what so much time is spent during installation or upgrade to new MacOS. In other words: having strongest machine (MacbookPro) with fastest hard drive (1GB/s read/write abilities) and having fast internet connection (30Mbps) - why update between two consequent minor version (i.e. from 10.12.2 to 10.12.3) takes 30 minutes - even if update declared to be 800 MB in size. I expect in answers mentioning specific functional actions, if someone knows or can guess ones.
(If you can add anything to this list, it would be greatly appreciated.)
- Firmware updates
Each and every macOS installer includes a firmware update package that has to run before the "regular" install process can be begun.