Device heats up while using webRTC

Hello everyone
We are developing chat application on android and ios using react-native-webrtc. There are such features like video and audio calls in our app. IOS devices, that we test our app on, all heat up very quickly, specifically when device is on active call (doesn’t matter audio or video stream is available). I checked Skype (mobile app) and seems like they have this problem either. Do you have any information about that?