Turn off any unnecessary settings int he BIOS.
Here are some things I set specifically:
- Turn off IDE detection on any IDE channels with no devices.
- Turn off the ability to boot from USB
- Remove any devices from teh boot order that you won't try to boot from, including USB.
- Turn off FDD and FDD seek if you have no FDD.
- Turn on "fast boot" or "quick boot" mode, if your BIOS supports it. That setting does faster checks that are less thorough.
Also understand that most people don't do a full boot, but resume from hibernation or standby, which takes far less time than a full boot. The sub-20s startup time is likely not a full boot, but resuming from hibernation or standby mode, either of which are far faster than a full boot.