It's possible to optimize the Fedora 17 boot process to boot the system in less than three seconds. One developer went from a boot time of 15 seconds down to just 2.5 seconds.
Harald Hoyer, a Fedora developer, has written a guide about Fedora 17 Boot Optimization
that goes over the steps he did to boot an Intel Core i5 laptop with an SSD in just 2.5 seconds. This was done with an EXT4 file-system, disabling the initramfs, kernel command-line parameters to save time during the kernel initialization process, turning off unneeded Fedora services, disabling SELinux, and making other small tweaks.
This amazing Fedora 17 boot speed comes just a few weeks after talking about a two second boot time with systemd