OP: First off, do not listen to these ignorant people who will tell you to upgrade. I am glad you are still on iOS 6. That reflects that people are still using it and not upgrading to the crap that iOS 8 is. I bet you anything your iPhone 5 performs better than the iPhone 6/6+ in terms of fluidity. Your iPhone 5 will also get the best battery life on iOS 6.1.4. DO NOT UPGRADE IT. Your battery usage will go drastically down. iOS 8, yet alone 8.4 performs like crap on the iPhone 5. It's laggy and animations stutter almost all the time.
Keep your phone on 6.1.4 for as long as you can. You will gain nothing by upgrading it, except a childish inspired OS full of horrible whites and abysmal icons. It will make your phone worse. Btw, your battery usage looks great.