Implement GameMode

hardware/gpu/amd.nix

···
   ];
 
   services.immich.settings.ffmpeg.accel = "vaapi";
+
+  programs.gamemode.settings.gpu.amd_performance_level = "high";
 }

hardware/gpu/nvidia.nix

···
   ++ lib.optional isLaptop "modesetting";
 
   hardware.nvidia = {
-    open = false; # Currently unable to build
+    open = true;
 
     modesetting.enable = isLaptop;
 
···
   );
 
   services.immich.settings.ffmpeg.accel = "nvenc";
+
+  programs.gamemode.settings.gpu.nv_powermizer_mode = 1;
 }

hosts/encryption/default.nix

···
 
     (flakeRoot + /modules/desktop)
     (flakeRoot + /modules/desktop/environments/gnome.nix)
+    (flakeRoot + /modules/desktop/system/gamemode.nix)
 
     ./users
   ];

hosts/prospect/default.nix

···
     (flakeRoot + /modules/common)
     (flakeRoot + /modules/common/boot/systemd-boot.nix)
 
+    (flakeRoot + /modules/desktop)
     (flakeRoot + /modules/desktop/environments/gnome.nix)
+    (flakeRoot + /modules/desktop/system/gamemode.nix)
 
     ./users
   ];

modules/desktop/system/gamemode.nix

···
+{
+  config,
+  lib,
+  isLaptop,
+  ...
+}:
+
+let
+  normalUsers = lib.attrValues (
+    lib.filterAttrs (_: user: user.isSystemUser == false) config.users.users
+  );
+in
+{
+  programs.gamemode = {
+    enable = true;
+
+    settings = {
+      general.renice = 10;
+
+      gpu.apply_gpu_optimizations = lib.mkIf isLaptop "accept-responsibility";
+    };
+  };
+
+  users.groups.gamemode.members = map (user: user.name) normalUsers;
+}