What exactly is dart doing in the background?

[rockingdice]

I opened a flutter project and don't do anything with it, the dart process is crazily running in the background. I don't know what is it doing?
How should I diagnostic this issue? Any logs?

[snechiporenko]

I have the same. And the laptop is very hot. It is impossible to work! Please fix this.

[DanTup]

I opened a flutter project and don't do anything with it, the dart process is crazily running in the background. I don't know what is it doing?
How should I diagnostic this issue? Any logs?

A few questions that may help narrow it down:

1. Does this happen if you create a new Flutter project and open that, or only with this specific project?
2. While this is happening, can you run code --status in the terminal and post the full output here?

Thanks!

[longtimedeveloper]

@DanTup I am also experiencing initial poor UI performance after opening any Flutter project now.

After preforming the below actions once, they work perfectly after that.

This can happen on small, medium, or large Flutter apps.

Summary of potential perf issues:

a. Intellisense can be very slow, displaying a 'loading...' overlay popup.

b. While typing, the editor shows the red squiggles until what I am typing is valid. For example, typing a partial field name would give you squiggles until you complete the field name. After I complete the field name, the red squiggles remain, even though the code is now valid after completing the field name. To get around this and remove the squiggles, I have to cut the line of code I was typing, save the file, then paste the code back in. I can also get the condition in d. below.

c. Find all references doesn't return any results, instead the linear progress bar displays but no results are found. When this happens, I use the Search in Files feature to find what I am looking for. Then later on, Find all references starts working normally.

d. When saving, the Formatter hangs. After a few seconds, a Formatting toast is displayed, and I click the 'Skip' button then the file saves. The next time this happens, I'll use the code --status command and post the results.

Unfortunately, the 4 above issues don't always happen after opening a project.

I hope this helps, best regards, Karl

My Installed vscode extensions

alefragnani.bookmarks@13.5.0
amiralizadeh9480.flutter-widget-wrap@0.0.3
dart-code.dart-code@3.114.2
dart-code.flutter@3.114.0
denoland.vscode-deno@3.45.0
esbenp.prettier-vscode@11.0.0
gmlewis-vscode.flutter-stylizer@0.1.16
gruntfuggly.todo-tree@0.0.226
miquelddg.dart-barrel-file-generator@7.4.1
nash.awesome-flutter-snippets@4.0.1
plibither8.remove-comments@1.2.2
rioj7.commandonallfiles@0.6.0
tamasfe.even-better-toml@0.21.2
tyriar.sort-lines@1.12.0
usernamehw.errorlens@3.26.0
vscode-icons-team.vscode-icons@12.13.0
yatki.vscode-surround@1.5.0

Code Status immediately after opening project

D:\code\flutters\apps\grocery_list>code --status

Version:          Code 1.101.2 (2901c5ac6db8a986a5666c3af51ff804d05af0d4, 2025-06-24T20:27:15.391Z)
OS Version:       Windows_NT x64 10.0.19045
CPUs:             Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz (8 x 4200)
Memory (System):  31.96GB (20.75GB free)
VM:               0%
Screen Reader:    no
Process Argv:
GPU Status:       2d_canvas:                              enabled
                  canvas_oop_rasterization:               enabled_on
                  direct_rendering_display_compositor:    disabled_off_ok
                  gpu_compositing:                        enabled
                  multiple_raster_threads:                enabled_on
                  opengl:                                 enabled_on
                  rasterization:                          enabled
                  raw_draw:                               disabled_off_ok
                  skia_graphite:                          disabled_off
                  video_decode:                           enabled
                  video_encode:                           enabled
                  vulkan:                                 disabled_off
                  webgl:                                  enabled
                  webgl2:                                 enabled
                  webgpu:                                 enabled
                  webnn:                                  disabled_off

CPU %   Mem MB     PID  Process
    0      147   11140  code
    1      442    5456  window [1] (app_initializer.dart - grocery_list - Visual Studio Code)
    0      247    6416  extension-host [1]
    0       96    1376       "C:\Users\gaudere\AppData\Local\Programs\Microsoft VS Code\Code.exe" "c:\Users\gaudere\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\json-language-features\server\dist\node\jsonServerMain" --node-ipc --clientProcessId=6416
   12      368    4140       D:\flutter\bin\cache\dart-sdk\bin\dart.exe language-server --protocol=lsp --client-id=VS-Code --client-version=3.114.2
    0       11    8392         C:\Windows\system32\conhost.exe 0x4
    0       90   12984       D:\flutter\bin\cache\dart-sdk\bin\dart.exe devtools --machine --allow-embedding --dtd-uri ws://127.0.0.1:59307/KEGcXY5TLHM=
    0       11   17684         C:\Windows\system32\conhost.exe 0x4
    0        5   13988       C:\Windows\system32\cmd.exe /d /s /c ""D:\flutter\bin\flutter.bat" "daemon""
    0       91    4916         electron-nodejs (config.js )
    0       11   17028         C:\Windows\system32\conhost.exe 0x4
    0       20   16796       C:\Users\gaudere\.deno\bin\deno.EXE lsp
    0       11    3124         C:\Windows\system32\conhost.exe 0x4
    0       39   17732       D:\flutter\bin\cache\dart-sdk\bin\dart.exe tooling-daemon --machine
    0       11    6540         C:\Windows\system32\conhost.exe 0x4
    0       15   14840         D:\flutter\bin\cache\dart-sdk\bin\dartaotruntime.exe --new_gen_semi_max_size=32 --new_gen_growth_factor=4 D:\flutter\bin\cache\dart-sdk\bin\snapshots\dart_tooling_daemon_aot.dart.snapshot --machine
    0      106   12436     gpu-process
    0      122   13480  pty-host
    0       88    7360       C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -noexit -command "try { . \"c:\Users\gaudere\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\contrib\terminal\common\scripts\shellIntegration.ps1\" } catch {}"
    0        5   10748       C:\Windows\System32\cmd.exe
    0      105   11316         electron-nodejs (cli.js )
    0      130   16360           "C:\Users\gaudere\AppData\Local\Programs\Microsoft VS Code\Code.exe" --status
    0       89    2216             utility-network-service
    0       99   12620             gpu-process
    0        6   14928       conpty-agent
    0        7   15276       conpty-agent
    0      174   14244  shared-process
    0      113   15580  file-watcher [1]
    0       45   17480     utility-network-service

Workspace Stats:
|  Window (app_initializer.dart - grocery_list - Visual Studio Code)
|    Folder (grocery_list): 286 files
|      File types: dart(54) png(26) xml(14) txt(12) log(8) json(6) lock(6)
|                  properties(6) bin(5) h(5)
|      Conf files: settings.json(1) cmake(1)

[DanTup]

@longtimedeveloper does this happen in a brand new project created with flutter create?

Can you also post the full output of flutter doctor -v? Thanks!

[longtimedeveloper]

@DanTup

Flutter Doctor -v

>flutter doctor -v
[√] Flutter (Channel stable, 3.32.3, on Microsoft Windows [Version 10.0.19045.6093], locale en-US) [482ms]
    • Flutter version 3.32.3 on channel stable at D:\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 5c1433509f (5 weeks ago), 2025-06-11 13:12:24 -0700
    • Engine revision 31c4875c7a
    • Dart version 3.8.1
    • DevTools version 2.45.1

[√] Windows Version (10 Pro 64-bit, 22H2, 2009) [1,378ms]

[√] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [3.0s]
    • Android SDK at C:\Users\gaudere\AppData\Local\Android\sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: C:\Program Files\Android\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 17.0.10+0--11572160)
    • All Android licenses accepted.

[√] Chrome - develop for the web [100ms]
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.14.4) [99ms]
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.14.36202.13
    • Windows 10 SDK version 10.0.26100.0

[√] Android Studio (version 2023.3) [23ms]
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.10+0--11572160)

[√] VS Code (version 1.101.2) [21ms]
    • VS Code at C:\Users\gaudere\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.114.0

[√] Connected device (4 available) [379ms]
    • sdk gphone64 x86 64 (mobile) • emulator-5554 • android-x64    • Android 15 (API 35) (emulator)
    • Windows (desktop)            • windows       • windows-x64    • Microsoft Windows [Version 10.0.19045.6093]
    • Chrome (web)                 • chrome        • web-javascript • Google Chrome 138.0.7204.158
    • Edge (web)                   • edge          • web-javascript • Microsoft Edge 138.0.3351.83

[√] Network resources [314ms]
    • All expected network resources are available.

• No issues found!

[longtimedeveloper]

@DanTup I just made a new project and did not experience any of the symptoms.

[snechiporenko]

I think the problem is with the first 2 processes.

[longtimedeveloper]

@DanTup today after I was editing my project for over an hour, I used the find all references feature for a class method. The progress bar was displayed and didn't find any references. I then search all files to find the places in the code where this method was called. The next time I used find all references, it work.

I also had the problem with Intellisense when adding an argument to a constructor. CTRL+Spacebar didn't work, and when typing, I got red squiggles. After about 30 seconds it started working.

I forgot to get the code --status I will try to remember to get this for you.

I hope this helps.

[DanTup]

Thanks for the info - there's an existing issue in the Dart SDK at dart-lang/sdk#55281 about these kinds of performance issues. Some of the comments seem like similar issues to what's being reported here, so I think we should centralise them all there because there are Dart devs reading and examining the reports being attached.

I'm not sure, but some of them could be related to dart-lang/sdk#60785 which was a bug in the parser that could result in an infinite loop. If you see the server using 100% CPU and never recovering, then I would try to see if you have any incomplete/invalid code that looks similar to what's shown there.

Otherwise, please follow the instructions in dart-lang/sdk#55281 (comment) (which includes details of how to export a diagnostic report and also collecting some info on analysis timers) and post them on to dart-lang/sdk#55281 along with a description of the problem, and the output of flutter --version or dart --version.

I'll close this one in favour of that, so all the reports are in one place.

Thanks!