rEFIt menu takes around 10 seconds to even show up
Assuming you have rEFIt installed on one of the partitions on the hard drive, the following steps should remove the delay:


Boot via the Mac OS X Install DVD/USB.
Launch Terminal (Utilities Menu).
Enter diskutil list to list all available disks and partitions.
Looking at the list of partitions for "disk0" (internal drive), identify the partition that contains your rEFIt boot files.
Enter bless --setBoot --device /dev/disk0s2 --legacy assuming that "/dev/disk0s2" was the rEFIt partition.
Enter reboot to reboot your Mac


Your Mac should now boot to rEFIt with a minimal delay.

The same method also works with Windows 7 direct booting (Boot Camp) which can present an extremely long boot delay on MacBook Airs and Minis if Windows 7 is your startup disk and the above steps have not been taken.