Windows: system-wide mouse stutter after Codex resumes from Modern Standby

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

26.810.4967.0 (runtime release: codex@26.810.41047)

What subscription do you have?

Pro

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

After the latest Codex update, leaving the computer idle for approximately 10–30 minutes causes system-wide mouse stuttering after returning from Modern Standby.

Fully closing Codex immediately stops the stuttering. Reopening Codex works normally until the next Modern Standby cycle.

Diagnostics captured while the mouse was stuttering

• ChatGPT.exe / Codex UI CPU: 18.1% in an 8-second sample
• Internal Codex snapshots showed main-process CPU peaks of 33.9%
• codex backend CPU: approximately 0.05–0.44%
• Approximately 18 GB of system RAM remained free
• DPC time: 0.19% average, 0.39% maximum
• Interrupt time: 0.45% average, 0.78% maximum
• CPU frequency: 2.64–3.13 GHz
• CPU performance limit: 100%
• No display-driver reset events were found
• App diagnostics contained 15 occurrences of:
  ResizeObserver loop completed with undelivered notifications
  within a recent 128-event diagnostic window

The mouse stutter affects the entire Windows desktop, not only the Codex window.

What steps can reproduce the bug?

1. Start the Codex desktop app.
2. Leave Codex open.
3. Leave the computer idle for approximately 10–30 minutes.
4. Windows enters Modern Standby due to idle timeout.
5. Resume the computer using the keyboard.
6. Move the mouse.

Power event evidence

• 15:59:13 — Kernel-Power event 506: entering Modern Standby, reason Idle Timeout
• 16:28:02 — Kernel-Power event 507: exiting Modern Standby, reason Input Keyboard
• 17:44:30 — entering Modern Standby, reason Idle Timeout
• 17:55:14 — exiting Modern Standby, reason Input Keyboard
• 19:42:42 — entering Modern Standby, reason Idle Timeout
• 19:59:37 — exiting Modern Standby, reason Input Keyboard

The issue reproduces after each idle/resume cycle. Restarting Codex only fixes it temporarily.

What is the expected behavior?

Mouse movement and the Windows UI should remain responsive after resuming from Modern Standby while Codex remains open.

Additional information

Environment

• CPU: Intel Core i7-1165G7, 8 logical processors
• RAM: 34 GB
• GPU: Intel Iris Xe Graphics
• GPU driver: 32.0.101.7077
• Display: 2560x1440 at 125% scaling
• Electron/Chrome runtime: 151.0.7922.137

Troubleshooting already performed

1. Fully restarted Codex multiple times.
   • Result: temporary recovery only.
2. Disabled Chromium hardware acceleration.
   • Result: no improvement; the setting was restored.
3. Set ChatGPT.exe processes to BelowNormal priority and excluded logical CPU 0.
   • Result: no improvement; the change was reverted by restarting the app.
4. Verified CPU throttling, RAM pressure, GPU usage, DPCs and interrupts.
   • Result: no system resource bottleneck was identified.

Regression information

The issue started immediately after updating to the current Codex desktop app version. It did not occur with the previous version.

No raw profile or Sentry files are attached because they may contain account or session identifiers.

Start by reproducing the Modern Standby and resume sequence with Codex left open, then inspect the captured CPU data and the app diagnostics for repeated ResizeObserver loop completed with undelivered notifications events. Compare behavior with the previous app version and verify that mouse movement and the Windows desktop remain responsive after each resume without restarting Codex.