Consider buying Snappy. You can find it in Cydia in the default repos, and I think it's only a couple bucks.
It allows you to use Activator to customize its launch commands, and it starts up in about a fifth of the time the native camera app takes to get going. It doesn't replace anything, it just gives you another, more streamlined camera program that you can start from the lock screen. I use it all the time; it's definitely worth the purchase.