Codex VS Code: after code changes impossible to continue in the same chat thread because of performance issue
What version of the IDE extension are you using?
0.5.75
What subscription do you have?
Plus
Which IDE are you using?
VS Code
What platform is your computer?
Microsoft Windows NT 10.0.26200.0 x64
What issue are you seeing?
After letting the agent cook for a while on quite some code changes (but not more than a few hundred lines of code), the chat/prompt box becomes unusable. Typing a single character gets a second of latency and high cpu.
Scrolling through chat history is fine -- but not when getting at the bottom that is showing the "files changed summary", then scrolling is slow and high cpu too. Thats why I think this "summary" is the culprit, but just guessing.
<img width="769" height="311" alt="Image" src="https://github.com/user-attachments/assets/6df44a55-7513-4541-8e39-accbab2dba94" />
What steps can reproduce the bug?
Just let it make (larger, few hundred lines) code changes, and at the end showing that "files changed summary".
What is the expected behavior?
I expect to be able to add more prompts without typing latency.
Additional information
I have a session thread id uploaded: 019c6abc-eb27-7f91-a2aa-1829590f7f83.
Using VSCode devtools and deleting html elements from the chat pane:
- Removing the summary alone: no improvement
- Removing all those expandable 'code blocks' in the chat history showing file changes: performance problem is gone.
<img width="629" height="151" alt="Image" src="https://github.com/user-attachments/assets/0f96f9eb-aaa1-4c8b-a336-3b7a4216bffd" />
PS: simply manually collapsing these 'code blocks' also solves the perf problem
6 Comments
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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Same problem here. What i do most of the time when it gets too laggy, shitf+ctrl+p -> "restart extension host" and resume the session.
You get the same performance problem with two instances of VSCode running both with a separate Codex chat thread. When the first VSCode instance has a Codex chat with some of those code blocks expanded and causing a perf problem in that thread, then also the second VSCode instance Codex chat thread, even though it is still empty, has the same performance problem. Fix is the same, collapsing the code block in the first instance. Just something I would not have expected to happen -- some sync going on I assume that is lagging.
@msneijders, just to confirm, are you saying that you're trying to open the same thread in two different instances of Codex at the same time? I wouldn't recommend that. It's fine to open a thread in a different instance after you've closed it in the first.
@etraut-openai I opened a second new thread (but without prompt yet I think) in that other vscode instance, but got me the same perf problem when the "slow" thread is still active in the other vscode instance -- I only noticed this once yesterday, and thought I mention it here, I might not have it consistently, I will let you know.
Tangentially related UX thread: #14045\n\nThis VS Code perf bug is different, but both issues touch the usability of the prompt box during long sessions/history inspection. #14045 proposes sticky composer behavior while scrolling chat history.