kexec is a handy tool which allows you to perform faster reboots. kexec works by using the existing kernel that is already in memory to boot again. The result is that you do not have to see the BIOS screen again, the new kernel will execute immediately after the system has halted.
To install kexec on a Debian/Ubuntu system, use the following commands:
apt-get install kexec-tools dpkg-reconfigure kexec-tools
This will make kexec your default handler for reboots. Should you ever need to do a cold reboot again, you can use /sbin/coldreboot.