Codex app on MacBook-pro (M4-max) - Massive CPU usage on startup for 55 seconds + Massive performance issues and lag + Response breaking #11584

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

260210.1703 (602)

What subscription do you have?

Pro

What issue are you seeing?

System:
MacOS Sequioa 15.7.3 (24G419)
MacBook pro Apple M4 Max - 64gb

Latest update very partially fixed the issue documented in previous threads found here:

• macOS app consumes 99% of CPU even when idle on a M4 Max - App completely broken #11299
• [Bug]: Massive CPU usage (100%+) and overheating (100°C) on M4 Mac Air - Version 260208.1016 #11124

However the app is still broken on my system due to massive performance issues. Creating new issue as requested by @etraut-openai in thread #11299.

Upon starting the app, it still consumes 100% of CPU for exactly 55 seconds. The 55 seconds is consistent, if you close the app and start it up again the same behaviour and timing repeats exactly. The main process is the "Codex" app for 55 seconds, then at 55 seconds CPU usage drops as "Codex Helper (Renderer)" and git take over for a few seconds (but they do not nearly consume as much CPU). This initial minute is enough to significantly heat the laptop and cause thermal throttling.

After this initial 55 seconds, if you leave the app idle, CPU usage intermittently spikes to roughly half of max capacity every few minutes (again, causing significant heating). If you're navigating the UI or writing a prompt, every time such a spike occurs, the app freezes for roughly a second.

I tried starting a thread but upon doing so CPU usage spiked massively for 2-3 minutes, and the app became practically unresponsive. The thread was started, with the agent starting to respond to the request, but the interface updated roughly every 5 seconds. CPU usage seemingly dropped after the initial 2-3 minutes or so on activity monitor, but the app remained extremely laggy and CPU usage spiked intermittently. Finally, after 5-10 minutes, the thread just crashed, leaving my prompt with an empty response.

The codex CLI and VSCode extension, in comparison, rarely go over 5% CPU usage at any point during regular usage.

Downgrading to version Version 260205.1301 (554) fixes the issue. The initial perfomance issues were introduced in Version 260206.1448 (where CPU usage was at 100% continuously). The difference is stark and not a difference of degrees, version 260205.1301 rarely goes above 5-10% CPU even during usage and is perfectly usable, and has no equivalent CPU usage spike on startup. Whatever issue got introduced in version 260206.1448 is still present, although behaving differently than before.

Summary
In summary, the macOS codex app is still suffering from massive performance issues on my system to the point of being unusable. It is a clear bug initially introduced in the 260206.1448 update, which disappears entirely upon downgrading to earlier versions. The latest update changes the behaviour somewhat, but the app is still broken overall. It uses 100% of CPU on startup for a consistent 55 second period, intermittently spikes to 50% CPU usage when idle, and spikes to 100% when used followed by crashing of requests.

What steps can reproduce the bug?

Start the macOs app on my system and attempt to use it.

What is the expected behavior?

No response

Additional information

Attempted to review the System diagnostic file with Codex 5.3, but no relevant info was captured (or extracted by Codex). If desired I can replicate the issue with whatever logging features you prefer and share the results.