gnome-shell-extension-gamemode - 8-2 main

GameMode optimises your system for peak performance when running a game.
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This shell extension will show you whether GameMode is active and for which
windows.
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If you have the Debian gamemode package installed, you can test this
extension by running: /usr/libexec/gamemode-simulate-game
which should pop up a notification that gamemode is running, and
that it has stopped after 10 seconds.