The routine Windows updates do go pretty quickly, but the "cumulative updates" can still take a very long time in my experience. I have to patch multiple servers and workstations at my job and it sucks. And if you have a hyper-v guest that lies dormant most of the time, but you need to update it once or twice a month, may the gods help you. Takes forever to even CHECK for updates, because Windows freaks the hell out if your PC remains turned off for a period of time.