Using 4S now for around 3years. With total battery cycles arnd 980 and total capacity around 1150mAH out of 1430. I get a usage around 4hrs without any games only Whatsapp, Facebook, Messages, Browsing and sometimes i watch videos on Protube. None of the iPhone has urged me to upgrade because i think if it's working and doing my daily tasks then there's no need to upgrade. But it becomes very laggy and even settings.app sometimes take few seconds to load and sometimes it works fine. What you guys say? Replace the battery or buy 6?