The Glympse app has been developed to maximize efficiency and minimize the amount of battery consumption, as best as possible. In order to provide real-time location sharing, Glympse utilizes the device's internal GPS, which uses a modest amount of battery.
Glympse utilizes a greater percentage of battery usage during an active Glympse and when the app is in the foreground. When the app is in the background, the app uses very little battery. When the app is actively sharing your location, it requires more battery usage due to the use of GPS on your device.