When I use the restart option in Windows 8, it takes longer to shut down and reboot then if I had used the manual shutdown and manual power on. I use an SSD and UEFI, and it happens on both of my computers. Any idea why it’s doing this or how to make reboot faster?
It's the expected behavior. This developer blog post explain that choosing shutdown will close your user session (where your average app run), but hibernated your kernel session (this is where driver lives). Thus, starting up won't require the driver initialization (which would cut the time if some particular drivers load longer or blocked others). Choosing restart would trigger the driver initialization, just like on Windows 7.