Massively Degraded WebGPU performance

[cshenton-work]

Bevy version

main#cf70f532

Relevant system information

Windows 11, Chrome

What you did

Even a basically empty application has severely degraded performance on main on WebGPU. The following:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins((DefaultPlugins,))
        .add_systems(Startup, (setup,))
        .run();
}

fn setup(mut commands: Commands) {
    commands.spawn((Camera3dBundle { ..default() },));
}

Results in a profile that looks like this:

That prepare_windows system is one of the culprits but generally speaking just everything is taking ages.

If I instead build against the 0.12.1 release on crates.io, I get a clean profile:

Something has clearly gone awry.

[alice-i-cecile]

Are you able to bisect the commit history? I suspect there was a single PR responsible.

[cshenton-work]

Yeah happy to, I shall report back if I find it.

[cshenton-work]

Afaict the regression was introduced by #10702

3b59dbd has a clean profile
ced216f has the performance issues I see

[cshenton-work]

3b59dbd

ced216f

Admittedly that is a particularly bad profile, it typically looked like the original post.

[alice-i-cecile]

FYI @Vrixyz, who has been tracking follow-up tasks in #11052.

[Vrixyz]

Thanks for providing such detailed report!

I'll still ask for more information, how are you running your app ?

There's a thin chance you're hitting #10702 (comment), Are you setting explicitly the width/height of your canvas ?

[daxpedda]

I'm going to assume that this is still the same as #11122.
I noted how this can be fixed in #11052 (comment): by using WindowEvent::RedrawRequested, otherwise drawing happens way too often.

[alice-i-cecile]

Closing as a duplicate :) Traces and replication were super useful though.