1The cause of the constant CPU usage could be the sound. If you do not need sound in your emulator you can disable it by editing the AVD's config file.
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3Change/add those two lines
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5hw.audioInput=no
6hw.audioOutput=no
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8Update: As buncis commented you can also try to disable GPS if not needed:
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10hw.GPS = no
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12On Linux/Mac the file is located at ~/.android/avd/<AVD_Name>.avd/config.ini
13On Windows the file is located at C:\Users\<username>\.android\avd\<AVD_Name>.avd\config.ini
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