Android Camera very hot, high temperature. Suggestion for a suitable android device

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I use openCV for android. My application find item at preview of camera. I use JavaCameraView.

Everything is stable on the device. But with Nexus 5 (Android 6.0), the device becomes overheated, battery decreases fast.

I think that problem to stay in the camera. What is the best device for opencv? What is the best camera?