3D performance issues

[Pyxrs]

I recently started using a laptop to work on my 3D bevy game in v0.18.1, where I noticed incredibly bad performance that was not present in other games. I was able to reproduce the issues just by running the 3d scene example; on v0.12.1 and before, I average ~2.3 ms. On v0.13.0 and after, it jumps up to ~16.7 ms average. The performance seems to be flatly about 8 times worse than it should be. In the atmosphere example in v0.18.1 my frame times are over 60ms, with my CPU usage fine but my GPU pinned at 100%. I narrowed down the problematic commit to the same one referenced in discussion #13771, which is 35ac1b1. Their issues were dismissed as a result of their CPU's age, but I appear to have the exact same problem with an AMD chip released in 2025. I also have the same GL crashing issue. I dual booted a KDE Plasma NixOS installation and it has the same problem. Drivers and BIOS are up to date. If it's a wgpu issue, then it exists from v0.19 all the way to v28 which I tested on the main Bevy branch.

Rust version: cargo 1.95.0-nightly (ce69df6f7 2026-02-12) (I also tested stable)

SystemInfo { os: "Linux (CachyOS Linux rolling)", kernel: "6.19.6-2-cachyos", cpu: "AMD Ryzen AI 5 340 w/ Radeon 840M", core_count: "6", memory: "13.4 GiB" }
AdapterInfo { name: "AMD Radeon 840M Graphics (RADV KRACKAN1)", vendor: 4098, device: 4372, device_type: IntegratedGpu, driver: "radv", driver_info: "Mesa 26.0.2-arch2.2", backend: Vulkan }

Code I'm running to test the issue:

use bevy::{
    diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
    prelude::*,
    window::PresentMode,
};

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins.set(WindowPlugin {
                primary_window: Some(Window {
                    present_mode: PresentMode::Immediate,
                    ..default()
                }),
                ..default()
            }),
            LogDiagnosticsPlugin::default(),
            FrameTimeDiagnosticsPlugin,
        ))
        .add_systems(Startup, setup)
        .run();
}

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    // circular base
    commands.spawn(PbrBundle {
        mesh: meshes.add(shape::Circle::new(4.0)),
        material: materials.add(Color::WHITE),
        transform: Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::FRAC_PI_2)),
        ..default()
    });
    // cube
    commands.spawn(PbrBundle {
        mesh: meshes.add(shape::Cube { size: 1.0 }),
        material: materials.add(Color::rgb_u8(124, 144, 255)),
        transform: Transform::from_xyz(0.0, 0.5, 0.0),
        ..default()
    });
    // light
    commands.spawn(PointLightBundle {
        point_light: PointLight {
            intensity: 250_000.0,
            shadows_enabled: true,
            ..default()
        },
        transform: Transform::from_xyz(4.0, 8.0, 4.0),
        ..default()
    });
    // camera
    commands.spawn(Camera3dBundle {
        transform: Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..default()
    });
}

Should I open an issue with wgpu? Just looking for guidance because I'm a bit out of my depth here :)