codex - 💡(How to fix) Fix Windows ARM64 running Codex App in Emulation [1 comments, 2 participants]

What version of the Codex App are you using (From “About Codex” dialog)?

26.406.31014

What subscription do you have?

Plus

What platform is your computer?

Windows 11 26H1 Arm64 (Microsoft Surface Pro 11 ARM)

What issue are you seeing?

The Codex Windows application is distributed without native ARM64 support.

On an ARM64 Windows device, all Codex processes (Codex.exe) run as x64 binaries under emulation, while other applications (e.g. VS Code) run as native ARM64.

This is visible in Task Manager:

• Code.exe → ARM64
• Codex.exe → x64 (emulated)

This indicates that the Codex app is not compiled for ARM64 Windows and relies on x64 emulation.

In addition to architectural mismatch, this leads to real usability issues:

• UI periodically freezes for a few seconds
• noticeable input lag during interaction
• occasional unresponsiveness under normal usage

These issues are not observed in native ARM64 applications on the same device, even vscode's version of Codex extension runs smoother.

Screenshot attached for reference.

<img width="1034" height="858" alt="Image" src="https://github.com/user-attachments/assets/50cc616b-37c7-4d67-9f86-10c9b8ee535c" />

What steps can reproduce the bug?

1. Use an ARM64 Windows device (e.g. Surface Pro 11) or a Windows 11 ARM64 VM in Parallels
2. Install Codex app from Microsoft Store
3. Launch the application
4. Use the app normally (navigation, input, interactions)
5. Observe periodic UI freezes and lag
6. Open Task Manager and confirm Codex.exe runs as x64

Result:

• UI freezes and lag occur during normal usage
• Codex runs under x64 emulation instead of ARM64

What is the expected behavior?

The application should provide a native ARM64 build for Windows, similar to macOS Apple Silicon support.

This is especially relevant given the distribution through the Microsoft Store, which supports multi-architecture packaging (similar in concept to macOS universal binaries).

Currently, the absence of an ARM64 build contradicts the expectations set by this distribution model.

Expected:

• Codex.exe runs as ARM64
• smooth and responsive UI without freezes
• no reliance on x64 emulation

At minimum:

• clear communication about ARM64 support status and roadmap

Additional information

The UI freezes strongly suggest that x64 emulation negatively impacts runtime performance.

Windows on ARM is actively promoted by Microsoft, and major developer tools (e.g. VS Code) already provide native ARM64 builds.

The Codex App is featured in the AI Hub of the Microsoft Store, including on Copilot+ PC devices.

However, it lacks native ARM64 support, which is a core characteristic of the Copilot+ PC ecosystem.

This creates a mismatch between platform positioning and actual application capabilities.

The lack of ARM64 support creates a platform inconsistency, especially since macOS ARM (Apple Silicon) is already supported natively.

This gives the impression that Windows ARM is treated as a lower-priority platform, despite real performance issues affecting users.