Gamemode
Gamemode is a daemon/lib combo for Linux that allows games to request a set of optimisations be temporarily applied to the host OS and/or a game process.
Installation
Install gamemode and lib32-gamemode.
Configuration
Create and configure a gamemode.ini file. An example gamemode.ini file can be found here. Save it in /etc/, $HOME/.config/ or /usr/share/gamemode/.
You may want to make sure that desiredgov is set to performance and maybe increase the renice to 10 or so for higher priority for your game.
Note that this package comes with a drop-in file etc/security/limits.d/10-gamemode.conf that allows for the renicing feature to work. If you wish to use to have gamemode renice game processes, you will want to create and join the gamemode group.
Usage
To run games with gamemode start it like this:
$ gamemoderun ./game
When you have started your game you can verify that gamemode is running with the command:
$ gamemoded -s
Steam
To make sure Steam starts a game with gamemode, right click the game, select Properties..., then Launch Options and enter:
gamemoderun %command%