The emulator qemu-system-i386.exe cpu usage almost constantly running between 7~9
Android studio 2.1 Android SDK Tools: 25.1.3 Host Operating System: Windows 7 - i7
To find out what on the virtual device is using the most CPU:
adb shell
$ top
This will show you a list of processes with the highest CPU usage atop.
This will help you determine whether it's a process (such as your app) inside the emulator, another process inside the emulator, or just the emulation itself using a lot of CPU.
In the latter case, try optimizing the emulator by installing HAX (Native intel instructions) or perhaps enable hardware acceleration using the AVD profile editor.