is it still worth developing for iphone 4?

first of all…greetings to all the lovely indie developers ,about my question : the problem is that my game runs 60 fps solid on all iOS devices that came after iPhone 4 but runs bad on the iPhone 4 with fps jumping between 13 and 40 and not stable at all ,
so it it still worth developing for it or i just skip it ??? i need your advices in this matter

Have a look at these resources:

Ultimately whether or not you choose to support any given device is up to you, but they should help you make an informed decision.