The Evad3rs have released an updated version of the Evasi0n jailbreak utility that improves device boot times following jailbreak.
What##Q##s New in Version 1.5:
– Improved boot-up time.
– Updated included Cydia package list.
Here are the Evasi0n Download Links.
If you are planning to update your device to iOS 6.1.2 you should make a backup and properly restore your device in iTunes. Do NOT use the over-the-air update.