I have a Mini late 2012. I do confess I have the stock HDD for the system. No upgrade to an SSD. I have two boot partitions. One has Sierra that I use for music recording. In that configuration I have 3 usb midi controllers, a usb audio interface, an ext fw recording hdd, 2 hdd's in a 2 slot usb bare drive dock and 2 usb hubs connected and a couple copy protection dongles. The other I use Mavericks so I can keep using Photoshop CS5 & 6 and Lightroom 5 & 6. The only peripherals I use then is a usb with just my keyboard, a drawing tablet and an ext hdd I have tutorial videos on. All that other stuff I use for music recording is off. What I notice is that when I use a bare number of peripherals, the computer boots in a certain 'x' amount of time. However, if the next time I boot up with my full whack of peripherals, it's like I can hear the computer having to rethink how the new config is different from the previous one. I realize the computer needs to 'poll' the various devices, but, geez, sometimes it's taking 3,4,5 minutes to boot up. Thing is, if I do stay on one particular config and boot, the computer is probably 'thinking'... 'ah, no changes made' and in that case doesn't take as long.