Mafia Definitive Edition is a remake of the 2002 classic game. It follows the rise and fall of Tommy Angelo, a Sicilian American taxi driver-turned-gangster, within the Salieri crime family in the fictional city of Lost Heaven, Illinois, during the 1930s.
Enabling AMD RSR
This is important, Launch the game first and put the game to Fullscreen mode and 720p resolution. Exit the game and open up the command center and turn on AMD RSR.
Open up the AMD Software in your task bar.
Click the AMD Software icon in your task bar.
Go to the gaming tab, click the game you want to enable AMD RSR on and enable it with borderless fullscreen in the settings. You can adjust the sharpness here as well.
In the preferences tab inside AMD Software you can enable the In-Game Overlay so you can see if AMD RSR is enabled when a game starts. (the shortcut key is alt + r)
Create A 900p Resolution
Using the 900p resolution gives you a performance boost without having to drop all the way down to 720p. You can learn how to create the custom resolution here.