Windows app significantly slower when impeller enabled (Gone when on skia)

### Steps to reproduce

After enabling impeller by updating to flutter 3.47.0 my windows application is noticeably slower.

When disabling impeller using: `--no-enable-impeller` my app runs like normal.

### Code sample

(edit gaaclarke: another use supplied a reproduction in https://github.com/flutter/flutter/issues/191353#issuecomment-5355205570)

### Performance profiling on master channel

- [x] The issue still persists on the master channel

### Timeline Traces

no idea how to collect this

### Video demonstration

Video demonstration (Impeller)

https://github.com/user-attachments/assets/5b374f60-7513-4f68-97de-d8ea411534dd

Video demonstration (Skia)

https://github.com/user-attachments/assets/ef026fb6-104e-4bbb-8968-92a5f97b4905

### What target platforms are you seeing this bug on?

Windows

### OS/Browser name and version | Device information

### Does the problem occur on emulator/simulator as well as on physical devices?

Unknown

### Is the problem only reproducible with Impeller?

Yes

### Logs

_No response_

### Flutter Doctor output

Doctor output

```console
[√] Flutter (Channel master, 3.48.0-1.0.pre-292, on Microsoft Windows [Version 10.0.26200.9106], locale en-BE) [4.2s]
• Flutter version 3.48.0-1.0.pre-292 on channel master at C:\Users\xxx\fvm\versions\master
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 65dec05eee (67 minutes ago), 2026-08-19 12:16:32 +0000
• Engine revision 65dec05eee
• Dart version 3.14.0 (build 3.14.0-143.0.dev)
• DevTools version 2.61.0-dev.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, enable-riscv64

[√] Windows Version (Windows 11 or higher, 25H2, 2009) [1,568ms]

[√] Android toolchain - develop for Android devices (Android SDK version 36.1.0) [2.6s]
• Android SDK at C:\Users\xxx\AppData\Local\Android\sdk
• Emulator version 36.3.3.0 (build_id 14204996) (CL:N/A)
• Platform android-36, build-tools 36.1.0
! Multiple adb binaries found. This can cause conflicts and device detection issues:
- C:\Users\xxx\AppData\Local\Android\Sdk\platform-tools\adb.exe
- C:\xxx\scrcpy-win64-v3.1\adb.exe
• 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 21.0.8+-14196175-b1038.72)
• All Android licenses accepted.

[√] Chrome - develop for the web [225ms]
• Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.14.18 (October 2025)) [223ms]
• Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
• Visual Studio Community 2022 version 17.14.36616.10
• Windows 10 SDK version 10.0.26100.0

[√] Connected device (2 available) [513ms]
• Windows (desktop) • windows • windows-x64 • Microsoft Windows [Version 10.0.26200.9106]
• Chrome (web) • chrome • web-javascript • Google Chrome 150.0.7871.101

[√] Network resources [497ms]
• All expected network resources are available.

• No issues found!
```

Start with the supplied Windows reproduction and compare performance with Impeller enabled versus `--no-enable-impeller`. Run the reproduction on the master channel, collect the missing timeline traces, and use the videos and Flutter Doctor output as context. Done means identifying the Impeller-related source of the slowdown and demonstrating that the Windows app returns to comparable performance without disabling Impeller.

Written by the indexing model from the issue text.