Slow FPS despite little CPU and GPU utilization

[Josh015]

Background
About 10 years ago I made a simple demo program called "Cubism" that utilized lots of cubes and lights as programmer art for my first big C++ OpenGL project. This week I decided to take Rust and Bevy for a spin by rewriting it with them as the new foundation.

Problem
I'm not sure what I'm doing wrong but it's SUPER sluggish. According to bevy's diagnostics plugins I'm averaging ~8fps when I run it. Though it's weird because task manager shows minimal CPU and GPU usage when the program is running. Also, I currently only have one light in the scene, and all the cube animations are pretty simple despite the large quantity of them on screen.

Question
Is anyone willing to take a look to see if I've made a noob mistake and did something obvious that's killing my performance? If so, the full "cubism-demo-rs" project is available online and doesn't require any special work to get running.

Thanks.

[bjorn3]

bevy_render currently is very much unoptimized. I think the low CPU and GPU usage mean that a lot of time is spent waiting on CPU to GPU transfers to finish.

[cart]

Are you building in release mode? I get over 200 fps on cubism-demo-rs

cargo run --release

And as @bjorn3 said, theres still plenty of optimization potential in Bevy.

[zicklag]

I get full smooth at least 60 fps ( I didn't measure ) when cubism in release mode on Linux.

[Josh015]

Hey, I finally got back here to see this. No, I wasn't doing "release" mode before, and yes it does make a shocking difference in performance.

Thanks for the tip.

[Josh015]

@cart FYI, thus far the porting process has been wonderful. Even in this early stage I absolutely love working with Bevy! 😁