Battery swap or new Phone

Hey i have a iphone 13 alpine green and the phone was fast and responsive but recently i noticed that my phone started to lag with IOS 26 and my battery health is at 80%, both of these problems make it literally unusable, i need to charge my phone at least twice a day. But futhermore it annoys me that it starts to lag even wenn i open snapchat or tiktok. And i noticed in the past few days that my wifi started not working, i tried reseting the network setting and updating to the latest software update, but it didnt help so I am frustated. So I wanna buy a new Phone ? I really like iPhones but should i buy a new one or replace the battery and the wifi module ?? Sorry for my bad english.