Codex app is laggy and unresponsive with long chat threads on Windows 11

[bvqbao]

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

26.429.61741

What subscription do you have?

Pro 5x

What platform is your computer?

Windows 11 x64

What issue are you seeing?

In a long chat thread, every time I enter a new message, the app becomes unresponsive for like 5s. After that it's still quite laggy. These problems didn't happen in some previous versions of Codex app with longer chat threads.

What steps can reproduce the bug?

In a long chat thread, post a new message.

What is the expected behavior?

The app should be responsive with long chat threads.

Additional information

No response

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• Codex Windows "not responding" freeze/hang with long chat/thread #19923
• Windows 26.429 desktop becomes unresponsive with long threads, MCP auto-start duplicates, and non-Git workspace warnings #20867
• Thread navigation/loading slows from unbounded metadata and eager large-history hydration #21211
• Codex Desktop becomes unusable on long active threads due to app-server/renderer memory and TRACE log churn #21134

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[carzygod]

Same issues meet .
Windows 11 . Codex GUI running without response and keep running CPU (signle core) stuck .
Version : Codex CLI 0.130.0

And , if the new session including image generate & display , it go display slow .

[egorx1]

Workaround: ask Codex to prune old local session JSONL files, then restart Codex App.

This solved my problem.

This can probably be automated locally by pruning old session JSONL files periodically.

[jinkeli66-gif]

Additional Windows reproduction with measurable renderer impact:

Environment

• Codex Desktop package: 26.715.2305.0
• Windows 25H2, build 26200.8875
• Intel Core Ultra 5 125H, 18 logical processors
• 16 GB RAM

Reproduction

1. Open a fresh/small Codex thread: the app remains usable.
2. Open one specific long, tool-heavy thread.
3. The entire desktop immediately becomes noticeably laggy.
4. Navigate away from the large thread and resource use/re responsiveness improves.
5. Reopening the same thread reproduces the lag every time.

The affected thread contains a long development history with many file changes, browser automation calls, screenshots/images, and large tool outputs. One run in that thread lasted about 43 minutes and reported roughly 493k cumulative tokens. This is not caused by the developed game/app itself: no game process is running when the lag reproduces; merely opening the Codex conversation is enough.

Observed during the lag

• Codex/ChatGPT processes: about 1.3 GB combined working set
• Codex GPU usage: about 13.8%
• Windows Desktop Window Manager GPU usage: about 10.1%
• Codex processes averaged about 9.7% total CPU during a 10-second sample
• The system has several GB of free memory and low disk queue, so the symptom is tied to loading/rendering the large thread rather than RAM exhaustion or disk saturation.

Expected
Opening a large thread should show the newest usable content quickly without hydrating/rendering the entire history synchronously.

Potential fixes:

• virtualize the message/tool-call list
• paginate/lazy-load older turns
• keep collapsed tool outputs and screenshots unmounted until expanded
• cancel/deprioritize old-thread hydration when the user navigates away
• provide a lightweight "continue in new thread with summary" action

This appears closely related to #21211, #22091, and #18693, but this report confirms a deterministic Windows case where simply entering one large thread causes immediate system-wide UI lag.