Ubuntu 9.04 Boots in 21.4 Seconds when using the EXT4 as the default filesystem. This is compared to Ubuntu 8.10 with EXT3 filesystem which boots in 26.8 seconds and Ubuntu 9.04 Alpha (Build 20090112.1) with EXT3 filesystem that boots in 24.5 seconds.

The boot times were calculated from the moment the GRUB boot loader appeared on the screen and until the login manager was displayed. As you can see, there is an approximately 8.7 second difference between an Ubuntu 8.10 (Intrepid Ibex) installation and an Ubuntu 9.04 Alpha (Jaunty Jackalope) one on the first system and 5.4 second difference on the second system.

Read more here: Ubuntu 9.04 Boots in 21.4 Seconds – With EXT4 as the default filesystem.