let's try without the custom overlays, maybe just enabling some flags will help performance

nixos/hosts/wheatley/configuration.nix

@@ -20,140 +20,6 @@
   powerManagement.cpuFreqGovernor = "ondemand";
   hardware.graphics.enable = true;
 
-  hardware.deviceTree = let
-    /*
-    Pin the raspberrypifw package to an old version.
-
-    - later versions bricked the devicetree so that HDMI wouldn't work anymore
-    - due to some changes around HDMI and audio for the rpi5?
-    - see: https://github.com/pftf/RPi4/issues/252
-    - the uefi firmware rolled back to a version of the raspberrypi/firmware repo before those
-      changes: https://github.com/pftf/RPi4/commit/6ba22a07bf19422c199dd801d3442319c04f5090
-    - they pinned it to b49983637106e5fb33e2ae60d8c15a53187541e4, so I'm doing the same on the
-      system level
-    */
-    raspberrypifw = pkgs.raspberrypifw.overrideAttrs {
-      version = "pinned-2025.03.27";
-      src = pkgs.fetchFromGitHub {
-        owner = "raspberrypi";
-        repo = "firmware";
-        rev = "f3465ff27e8795b9db6e088c383ec79464aa985e";
-        hash = "";
-      };
-    };
-  in {
-    enable = true;
-
-    # use the devicetree files from the official raspberrypi linux tree
-    dtbSource = pkgs.device-tree_rpi.override {inherit raspberrypifw;};
-    filter = "bcm2711-rpi-4-b.dtb"; # only apply overlays on the one devicetree I actually need
-    name = "broadcom/bcm2711-rpi-4-b.dtb"; # use and load the correct rpi4b devicetree
-
-    /*
-    Devicetree overlays applied to the main devicetree.
-
-    - these are applied during build, i.e. these are *not* passed separately to the bootloader
-    - they're compiled in beforehand, the resulting single dtb file is then given to the bootloader
-    - overlays are applied in the order they're in the list
-    - the upstream overlays by raspberrypi are in the raspberrypifw package, see `upstreamOverlay`
-    - these are documented in their repo: https://github.com/raspberrypi/linux/blob/rpi-6.6.y/arch/arm/boot/dts/overlays/README
-
-    See:
-    - https://docs.zephyrproject.org/latest/build/dts/intro-syntax-structure.html
-    - https://bootlin.com/blog/enabling-new-hardware-on-raspberry-pi-with-device-tree-overlays/
-    - https://elinux.org/Device_Tree_Source_Undocumented (for `/delete-property/`)
-    */
-    overlays = let
-      upstreamOverlay = name: raspberrypifw + /share/raspberrypi/boot/overlays/${name}.dtbo;
-    in [
-      /*
-      Fixes a bug I experienced with the mainline kernel where only one CPU core would work.
-
-      - I wrote this overlay to apply the changes from this patch I found online:
-        https://github.com/AntonioND/rpi3-arm-tf-bootstrap/blob/master/0001-rpi3-Enable-PSCI-support.patch
-      - there'd be "failed to come online" messages in `dmesg`
-      - I found the patch here: https://github.com/OP-TEE/build/issues/360
-      */
-      {
-        name = "custom-enable-method";
-        dtsText = ''
-          /dts-v1/;
-          /plugin/;
-
-          / {
-            compatible = "brcm,bcm2711";
-
-            fragment@0 {
-              target = <&cpus>;
-              __overlay__ {
-                /delete-property/ enable-method;
-              };
-            };
-
-            fragment@1 {
-              target-path = "/";
-              __overlay__ {
-                psci {
-                  compatible = "arm,psci-1.0", "arm,psci-0.2";
-                  method = "smc";
-                };
-              };
-            };
-
-            fragment@2 {
-              target = <&cpu0>;
-              __overlay__ {
-                enable-method = "psci";
-                /delete-property/ cpu-release-addr;
-              };
-            };
-
-            fragment@3 {
-              target = <&cpu1>;
-              __overlay__ {
-                enable-method = "psci";
-                /delete-property/ cpu-release-addr;
-              };
-            };
-
-            fragment@4 {
-              target = <&cpu2>;
-              __overlay__ {
-                enable-method = "psci";
-                /delete-property/ cpu-release-addr;
-              };
-            };
-
-            fragment@5 {
-              target = <&cpu3>;
-              __overlay__ {
-                enable-method = "psci";
-                /delete-property/ cpu-release-addr;
-              };
-            };
-
-          };
-        '';
-      }
-
-      /*
-      This overlay comprises the vc4-kms-v3d-pi4 and dwc2 overlays for graphics and USB.
-
-      - note that nixos-hardware uses the vc4-fkms-v3d-pi4 overlay instead
-      - fkms (fake/firmware kernel mode setting) uses a feature in the firmware blob, proper kms
-        implements mode setting itself
-      - https://forums.raspberrypi.com/viewtopic.php?t=255478
-      - the kms driver is newer, fkms is deprecated by upstream now
-      - fkms didn't work for me anyway
-      - kms does, but only with the pinned devicetree repo (see above)
-      */
-      {
-        name = "upstream-pi4";
-        dtboFile = upstreamOverlay "upstream-pi4";
-      }
-    ];
-  };
-
   nixpkgs.overlays = [
     (final: super: {
       makeModulesClosure = x: