You could try reducing the background tasks or a different 'cleaner' image which has less of the unnecessary background tasks already removed(i dont know how much of background processing the standard image of the R-Pi Zero takes) Might also try reducing the display resolution as then the GPU wouldnt have to work that hard. Also turn off Wi-Fi/Bluetooth if possible. These are just some of the things that jump out to me while attempting to make the Pi go QRP!
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