Needs to be updated

I have used this alarm app for a few years now and it works as advertised. However, after upgrading to iOS 10 I am getting a message from Apple that this app is slowing my iPhone and needs to be updated by the developer. Checking in the App Store I see that its last update was in September of 2013. Come on guys update the thing!!

Tom G. about Flip Clock - Weather Alarm Clock and Nightstand for iPhone, v1.6.3