New answers tagged iphone-3gs
iOS 4.2.1 is the fastest for iPhone 3GS. But many apps not support iOS 4 anymore. iOS 6 is faster than iOS 5 on 3GS – but big apps like Flipboard may be slow due memory limit on 3GS.
You can do the IMEI unlock, it costs $5 and you wont need to jailbreak anymore.
You're a few weeks too late. There was the Evasi0n jailbreak, which worked on iOS 6.0 - 6.1.2, but iOS 6.1.3 killed it.
Not a very good solution, but it should work. Once you send the file to your Mac (or Windows machine), and put it in iTunes, you can convert to iPhone-compatible format and sync back to your iPhone... Here is the iTunes menu choice for "Create and iPod or iPhone Version":
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