This program was created to provide you with an alternative to launching System Preferences for changing display settings. The application is very simple to handle, uses minimum CPU resources while running, and sits quietly on your Menu Bar from where you can select a different screen resolution.
Its main menu displays a list with all supported screen resolutions and options to detect connected monitors and to automatically launch the program at system login. You also have direct access to System Preferences -> Display settings panel in case you wish to have access to additional monitor options.
What's more, the application offers you multi-monitor support and shows you lists of supported resolutions for any screen that's being connected to your Mac.
Other than that, not much more can be said about Display Menu as it does exactly what's being said on its homepage. It works perfectly, doesn't slow down the performance of your system, and is free.
But, if you wish to have access to additional display settings and Retina support, you should upgrade this application to its Pro version. The acquiring price is very cheap and, in my opinion, it's definitely worth buying it.