[Windows] System-wide mouse and window-drag stutter; visible foreground Task Manager temporarily suppresses it

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

OpenAI.Codex 26.810.6296.0 (Chromium 151.0.7922.137)

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Microsoft Windows NT 10.0.22621.0 x64 (Windows 11 Home; OS build 22621.2715)

What issue are you seeing?

The unified ChatGPT/Codex Windows desktop app intermittently causes system-wide mouse-movement and window-dragging stutter after it has been running for some time.

Completely exiting and reopening ChatGPT restores smooth behavior, but the stutter can return later.

The strongest discriminator is that a continuously updating monitoring window suppresses the symptom only while that window is visible and in the foreground.

Environment

• Package: OpenAI.Codex_26.810.6296.0_x64__2p2nqsd0c76g0
• Executable: ChatGPT.exe
• Bundled Chromium: 151.0.7922.137
• Laptop: Acer Predator PHN16-71
• CPU/RAM: Intel Core i5-13500HX, 16 GB RAM
• Internal display: 1920x1200, fixed 165 Hz
• Intel UHD Graphics driver: 31.0.101.4146
• NVIDIA RTX 4050 Laptop GPU driver: 591.44
• Hybrid graphics; DxDiag reports the internal panel on the Intel integrated display path
• Virtual display adapters are installed (GameViewer, ToDesk, and Oray); they were not removed during this reproduction

What steps can reproduce the bug?

1. Completely exit and reopen the ChatGPT/Codex desktop app. Mouse movement and window dragging are initially smooth.
2. Use the app normally and leave it running.
3. After some time, system-wide mouse movement and window dragging begin to stutter. One observed recurrence happened after roughly one hour of app runtime.
4. Open Task Manager and keep its live graphs visible in the foreground. Mouse movement and window dragging immediately become smooth.
5. Minimize Task Manager, cover it with another window, or move it out of the foreground. The stutter immediately returns.
6. Leaving the Task Manager process running in the background is not sufficient.
7. Resource Monitor has the same suppressing effect while visible in the foreground.
8. A static foreground Notepad window does not suppress the stutter.
9. Completely exit and reopen ChatGPT. The stutter disappears, but can return after the app has been running again.

The symptom can also disappear while a ChatGPT/Codex task is actively producing updates and later return when the app becomes idle.

A pointer-timing probe attempted during an active task was discarded because the symptom was not present at that moment.

What is the expected behavior?

ChatGPT/Codex should remain open or become idle without causing system-wide mouse-movement or window-dragging stutter.

Additional information

Controlled exclusions

• Win+Ctrl+Shift+B did not change the affected state.
• Changing the NVIDIA preferred-GPU setting did not resolve the problem.
• The internal display was already using a fixed 165 Hz mode, not dynamic refresh rate.
• Intel PSR2 was disabled with PSR2Disable=1 and the setting was loaded by a reboot. The symptom still recurred after opening the desktop app.
• Temporarily closing PredatorSense did not resolve it.
• No ChatGPT.exe Application Error 1000 events were recorded since boot.
• A clean 15-second observation window recorded no PowerShell/WMI full-process snapshot calls involving Win32_Process, Win32_PerfFormattedData_PerfProc_Process, or Get-CimInstance.
• The local logs_2.sqlite was approximately 173 MB, not several GB.
• No repeated completed-thread replay loop was identified.

Affected-state measurements

The following 20-second sample was captured while the stutter was present and Task Manager was closed:

| Counter | Average | Maximum |
|---|---:|---:|
| Total CPU | 4.44% | 6.88% |
| DPC CPU | 0.18% | 0.54% |
| Interrupt CPU | 0.16% | 0.69% |
| Processor queue length | 0.55 | 6.00 |
| Physical-disk queue length | 0.01 | 0.05 |

In a later app-open sample, the ChatGPT.exe process group used approximately 1.08 GB working set and 2.28 GB private bytes. The busiest ChatGPT GPU and renderer processes used approximately 4.0% and 3.5% of one CPU core respectively. There was no total CPU saturation.

Related report

This may be related to #33258, but this reproduction adds several distinguishing observations:

1. It remains reproducible on 26.810.6296.0 with Chromium 151.
2. Completely exiting and reopening ChatGPT restores smooth behavior without rebooting Windows.
3. It reproduces on a hybrid-graphics laptop with a fixed 165 Hz internal panel.
4. The symptom is suppressed only when a continuously updating monitoring window is both visible and in the foreground. Keeping the monitoring process alive in the background is not sufficient.
5. There is currently no evidence supporting WMI polling, an Application Error 1000 crash loop, or completed-thread replay as the cause.

The foreground-visibility behavior appears consistent with a DWM/Chromium presentation, occlusion, or compositor-cadence interaction rather than CPU, disk, mouse hardware, or ordinary process priority. This is an interpretation, not a confirmed root cause.

If maintainers specify the preferred profile and a privacy-safe collection procedure, I can capture a bounded WPR trace with GPU, DesktopComposition, and input providers during a future affected window.