Payday 2 is one of the games I was extremely excited to start playing on my Steam Deck when it arrived, seeing as it was verified I had no doubts it wouldn't run at a solid 60 on at least medium, only to find out I could barely get 15 FPS on lowest.

While the game is listed as Verified, if you want any level of playable performance, you'll need to do some very minor tweaking yourself.

Thankfully it is extremely simple, all we need to do is get another compatibility layer for Proton, and this guide will show you how to set this up.

1) Swap your Steam Deck over into Desktop mode.

2) Go to the Discover Software Centre and search for ProtonUp-Qt, install it.

3) Under all applications, you'll find it under P, run the program.

4) It should open a window on the top right of your screen, click the "Add version" button.

5) The specific one I have used to get this to work as well as other games (Black Ops III) is "GE-Proton7-5". Select this specific version from the dropdown menu and hit install.

6) Swap back to Gaming mode.

7) Go to Payday 2 and select the settings button (Cog icon) and go to Properties > Compatibility

8) Select the Box that states "Force the use of a specific Steam play compatibility tool", this will open a drop down menu where you will select "GE-Proton7-5". (if you do not see this, try restarting your deck.)

9) Launch the game, your performance will be significantly better.

Hopefully this will repair your performance but I can only speak from my own experiences, I highly urge Overkill to look into making an official guide to repair the performance.

If you would prefer a video version, this guide to add the compatibility layer for Call of Duty: Black Ops III functions exactly the same (all credit to Monejha):
I hope this has helped you :)