Originally Posted by ext233
thanks for your reply. all i want to install are custom screensavers. i'm curious to hear other people's experiences too, though, regarding performance and battery life post-jailbreak.
"Jailbreak" is only an installer for custom certificate and rescue mode. The first one just allows you to install updates that are not signed by Amazon, and the second one is not used unless you want to. Nowadays there's also a bridge for reinstalling jailbreak after upgrades - which is only executed at boot time.
There is no physical way for it to affect performance or battery life.