Is it necessary to select a startup disk from within the Startup Disk control panel? I did not do it and it seems to take quite a long time for my computer to start up.

Power Macintosh computers that use the ROM-in-RAM (otherwise known as New World) architecture, such as the Power Mac G4 or PowerBook (FireWire), will take longer to start up unless the drive that contains the active system folder and the Mac OS ROM file is selected in the Startup Disk control panel.

If you do not have a drive selected there, the computer has to scan through all the available interfaces where a start up device can be found, including SCSI (if installed), IDE, any network port, and USB. This takes some time to do, so the length of time to start up the computer is extended.

All you need to do is select the appropriate disk in the Startup Disk control panel, on the next restart you should notice an reduction in the amount of time it takes to start up your computer.