Victor0_ASUSJust avoid the use of highest brightness and check under Settings>Battery what are the apps consuming more, it should be the culprit (or it's just the display brightness).
Please follow below steps:
1. Enable “Power saver” (Settings > Power management)
2. Close apps that are not used (Bluetooth, WiFi, GPS, etc.)
3. Adjust sleep time and brightness (Settings > Display)
4. Boost memory when you see memory consumption is high with no app running,
5. check for background running applications, stop/disable unwanted apps, you can manage apps from auto-start manager.