Same settings as the OP,
15 Threads and ran for 15 mins
Room Temp - 23°C
I am getting a better result but the thing is that I am still on 2.0.4 which to many people downgraded the performance to increase battery life.
The performance was already somewhat stable but around 5 mins it started clocking like crazy for unknown reasons then again settled after some mins. The max temp I noted was 44°C.
Battery drain - 3%
I do live in a humid and warm area with around 30 degrees at all times during the night so I am honestly surprised.