You may not want the Grub boot menu to sit for ~10 seconds on every startup.
There was a menu list file with previous builds of Ubuntu (Grub 1), but changing the Grub menu with the new version 2 is a little different.
Edit this file as root:
/etc/default/grub
Look for this line:
GRUB_TIMEOUT=10
Change to the value you want (in seconds), such as 5, save the file, then run
sudo update-grub