Usemon Monitors System Performance From the Notification Shade

Source: http://lifehacker.com/usemon-monitors-system-performance-from-the-notificatio-1181523575

Android: In Windows, seeing how fast your CPU is cranking is just a keyboard shortcut away. Android isn't as convenient. Unless you use Usemon.

The app puts an at-a-glance system monitor directly in the notification shade of your device. Just swipe down and get graphs for CPU, RAM, network, and disk usage. You can adjust which stats are shown in the shade (or disable them entirely) from the settings. Or you can deck out your shade with our previous round up of notification shade apps.

Usemon (Usage monitor) | Google Play Store via WonderHowTo