You can just create the gamemode group and then add your user to it.
Use gamemoded -t to test that it’s configured and working correctly. The configuration file should probably be /etc/gamemode.ini. And gamemoded -s tells if gamemode is currently active. Steam doesn’t support gamemode, so you have to add gamemoderun %command% to every game’s launch options.
Gamemode, that I mentioned in another message, among other things changes the niceness value.
That’s the thing. It’s most likely in your distro’s package manager, unless you are using CachyOS, which uses different app for the same thing. Remember to add your user to the gamemode group or it won’t do much for you.
Looks like Linux adoption has been skyrocketing since early this year in English speaking areas.
Try searching internet for something like: Linux proton crackling
Are you using gamemode, and have you added your user to the gamemode group? Crackling is likely caused by buffer underrun. Many reasons why that might happen, but one is that if the game isn’t given high enough privileges, the machine can’t fill the buffer quickly enough. Gamemode should solve that. Check your distro’s guide how to set it up. If that doesn’t work, Pipewire/PulseAudio might have been configured to use too short buffer.
There are also rumors that Microsoft will remove third-party apps like antivirus apps and anticheats from Windows kernel. If that happens, it will pretty much solve the anticheat problem for Linux as well.
Heroic Launcher should have a setting for gamemode.