How to improve device heating (Android)

Hello,

we are currently developing a 2D game for mobile devices. The game has no 3D elements, no custom shaders, nothing on scene but Unity UI elements. Draw calls in the scene never go over 30, and are usually around 20. We have almost no script overhead, and in the profiler we can't see any big issues.

Here is a screenshot for reference:

The issue is: our game uses a lot of battery and heats our test devices a lot.

We noticed that by locking the frame rate at below 30 fps the situation improves by about 5°, but we would like other suggestions, because our game is really graphically simple, so we don't see how one canvas, one camera and 20/30 draw calls can heat a device to up to 45/50 °C.

Thank you!