But unlike this (which is timed in hours) in Android it's done in a minute and then the notification is gone. Maybe Apple should start by doing the update in minutes first.
I find it really bizarre that it takes hours to run whatever background process iOS has after an upgrade, especially because in Android's case this is AFAIK rebuilding the Dalvik bytecode while iOS should use a compiled language (ObjectiveC/Swift).
Does someone knows what is iOS doing at the background?