As possibly the last feature to be accepted and implemented before the big release, Feral Interactive's GameMode performance tool has been added officially into Ubuntu 20.04 LTS.
What the heck is GameMode? It's a Linux "daemon", otherwise known as a background process and a library that games can hook into. Enabling games to request things like a little more power from your CPU, I/O priority, screensaver inhibiting and other optimizations. The goal is to make Linux gaming smoother. Games can integrate it (like newer Feral Linux ports) to use it automatically, or you can manually tell games to use it. You can see GameMode on GitHub.
For Ubuntu 20.04, the upcoming LTS (Long Term Support) release, it will be installed by default so you don't need to do any messing around. So you will be able to run any game with "gamemoderun ./game-exectuable" or for Steam add a launch option of "gamemoderun %command%" right out of the box and hopefully get the best experience. It's also been confirmed for default inclusion in Ubuntu MATE 20.04.
You can see the now solved report for GameMode in Ubuntu on Launchpad, where you can see the folks at Canonical giving it a security review and ensuring the Ubuntu and Debian packaging for it is nicely sorted.
Ubuntu 20.04 is due to release on April 23.