Hello, I have my old iPhone 3G that I want to update, but I'm a little bit lost.

its on 3.1.2, and I dont know to wich version, should I go for, to be able to Unlock it and Jailbreak it.

The only thing I know, is that I have to avoid iOS 5.xx, as it will slow my iPhone to hell.

Hope to hear from you.

Thanks in advance to everyone.