Very high CPU usage (~30% - 50%) on base / empty game on Linux

Reproduce using the provided pubspec.yaml and lib/main.dart with FlameGame, then build via flutter build linux and watch CPU with htop. First read the bare Flame game tutorial linked and profile the idle game loop. Done means the empty game sits at ~1% CPU like a default Flutter app.

What happened?

Using the recommended starting project, I see that htop shows the running application using 30% to 50% CPU. There are some bwrap child processes that quit after about 20 seconds, but the high CPU usage continues. I took a look at the CPU profiler in my browser, when running the application under profile mode, and there is no record of high CPU usage there.

If I run the default Flutter app in the same way, I get about 1% CPU usage or less while it's running.

I've seen this on Flame 1.38.2, 2.0.0-dev.1 and an older version like 1.31.0.

What do you expect?

I expected CPU usage by Flame to be around 1% or less when not drawing anything to the screen.

How can we reproduce this?

Follow the instructions for a new project, then run it like so:

flutter build linux && build/linux/x64/release/bundle/flame_tmp

Check your CPU profiler for the flame_tmp process.

What steps should take to fix this?

No response

Do have an example of where the bug occurs?

pubspec.yaml:

name: flame_tmp
description: "A test case for Flame"
publish_to: 'none'
version: 0.0.0+1

environment:
  sdk: ^3.13.5
  flutter: ^3.47.7

dependencies:
  flutter:
    sdk: flutter
  flame: ^1.38.2
  #flame_svg: ^2.0.0

lib/main.dart:

import 'package:flame/game.dart';
import 'package:flutter/widgets.dart';

void main() {
  final game = FlameGame();
  runApp(GameWidget(game: game));
}

Relevant log output

stdout / stderr:


[IMPORTANT:flutter/shell/platform/embedder/embedder_surface_gl_impeller.cc(126)] Using the Impeller rendering backend (OpenGLESSDF).
Gdk-Message: 22:56:58.439: Unable to load  from the cursor theme


These seem to be the processes that appear as children for a while:


andrew     14591  0.0  0.0   3876  2436 pts/0    S+   22:59   0:00 bwrap --unshare-all --die-with-parent --chdir / --ro-bind /usr /usr --dev /dev --ro-bind-try /etc/ld.so.cache /etc/ld.so.cache --ro-bind-try /nix/store /nix/store --tmpfs /tmp-home --tmpfs /tmp-run --clearenv --setenv HOME /tmp-home --setenv XDG_RUNTIME_DIR /tmp-run --setenv RUST_BACKTRACE full --setenv XDG_RUNTIME_DIR /run/user/1000 --symlink /usr/lib /lib --symlink /usr/lib64 /lib64 --ro-bind-try /etc/fonts/conf.d /etc/fonts/conf.d --ro-bind-try /etc/fonts/fonts.conf /etc/fonts/fonts.conf --ro-bind-try /home/andrew/.cache/fontconfig /home/andrew/.cache/fontconfig --ro-bind-try /home/andrew/.config/fontconfig/fonts.conf /home/andrew/.config/fontconfig/fonts.conf --ro-bind-try /home/andrew/.fonts /home/andrew/.fonts --ro-bind-try /var/cache/fontconfig /var/cache/fontconfig --bind-try /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg --setenv XDG_CACHE_HOME /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg --seccomp 24 /usr/libexec/glycin-loaders/2+/glycin-svg --dbus-fd 23
andrew     14592  0.0  0.0   3876  1408 pts/0    S+   22:59   0:00 bwrap --unshare-all --die-with-parent --chdir / --ro-bind /usr /usr --dev /dev --ro-bind-try /etc/ld.so.cache /etc/ld.so.cache --ro-bind-try /nix/store /nix/store --tmpfs /tmp-home --tmpfs /tmp-run --clearenv --setenv HOME /tmp-home --setenv XDG_RUNTIME_DIR /tmp-run --setenv RUST_BACKTRACE full --setenv XDG_RUNTIME_DIR /run/user/1000 --symlink /usr/lib /lib --symlink /usr/lib64 /lib64 --ro-bind-try /etc/fonts/conf.d /etc/fonts/conf.d --ro-bind-try /etc/fonts/fonts.conf /etc/fonts/fonts.conf --ro-bind-try /home/andrew/.cache/fontconfig /home/andrew/.cache/fontconfig --ro-bind-try /home/andrew/.config/fontconfig/fonts.conf /home/andrew/.config/fontconfig/fonts.conf --ro-bind-try /home/andrew/.fonts /home/andrew/.fonts --ro-bind-try /var/cache/fontconfig /var/cache/fontconfig --bind-try /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg --setenv XDG_CACHE_HOME /home/andrew/.cache/glycin/usr/libexec/glycin-loaders/2+/glycin-svg --seccomp 24 /usr/libexec/glycin-loaders/2+/glycin-svg --dbus-fd 23

Execute in a terminal and put output into the code block below

Output of: flutter doctor -v

[✓] Flutter (Channel stable, 3.47.8, on openSUSE Tumbleweed 7.3.0-1-default, locale en_US.UTF-8) [64ms]
    • Flutter version 3.47.8 on channel stable at /home/andrew/.local/lib/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 737ba8f885 (2 days ago), 2026-10-22 21:37:31 -0700
    • Engine revision cf636b1dfb
    • Dart version 3.13.7
    • DevTools version 2.60.0
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-native-assets, enable-record-use,
      enable-swift-package-manager, omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration

[✓] Android toolchain - develop for Android devices (Android SDK version 37.0.0) [483ms]
    • Android SDK at /home/andrew/Android/Sdk
    • Emulator version 37.2.12.0 (build_id 16428233) (CL:N/A)
    • Platform android-37.2, build-tools 37.0.0
    • ANDROID_SDK_ROOT = /home/andrew/Android/Sdk
    • Java binary at: /home/andrew/.local/lib/android-studio/jbr/bin/java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 21.0.8+-14018985-b1038.68)
    • All Android licenses accepted.

[✓] Chrome - develop for the web [17ms]
    • CHROME_EXECUTABLE = chromium

[✓] Linux toolchain - develop for Linux desktop [481ms]
    • clang version 23.1.3
    • cmake version 4.4.4
    • ninja version 1.13.2
    • pkg-config version 2.5.1
    • OpenGL core renderer: AMD Radeon 840M Graphics (radeonsi, krackan1, ACO, DRM 3.64, 7.3.0-1-default)
    • OpenGL core version: 4.6 (Core Profile) Mesa 26.2.5
    • OpenGL core shading language version: 4.60
    • OpenGL ES renderer: AMD Radeon 840M Graphics (radeonsi, krackan1, ACO, DRM 3.64, 7.3.0-1-default)
    • OpenGL ES version: OpenGL ES 3.2 Mesa 26.2.5
    • OpenGL ES shading language version: OpenGL ES GLSL ES 3.20
    • GL_EXT_framebuffer_blit: yes
    • GL_EXT_texture_format_BGRA8888: yes

[✓] Connected device (2 available) [806ms]
    • Linux (desktop) • linux  • linux-x64      • openSUSE Tumbleweed 7.3.0-1-default
    • Chrome (web)    • chrome • web-javascript • Ungoogled Chromium 156.0.8078.47

[✓] Network resources [238ms]
    • All expected network resources are available.

• No issues found!

Affected platforms

Linux, Web

Other information

I'm using OpenSUSE Tumbleweed, a rolling release distribution. My laptop is fairly recent, so it's not underpowered.

Are you interested in working on a PR for this?

• I want to work on this