[Windows] Severe mouse stuttering after launching Codex Desktop until pet/avatar overlay is opened and closed

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

26.810.50856

What subscription do you have?

Team

What platform is your computer?

Windows 11

What issue are you seeing?

[!IMPORTANT]

Temporary workaround

If Codex Desktop causes severe system/UI stuttering:

1. Open the Codex pet/avatar feature.
2. Close or disable the pet/avatar feature again.

On my system, the mouse and UI stuttering stops immediately after the pet/avatar overlay is opened once and then closed.

Issue

Simply launching Codex Desktop causes severe system/UI stuttering on Windows 11, including noticeable mouse cursor stutter.

The issue starts immediately after Codex is opened and does not require starting a task.

During investigation, I observed approximately 974 MiB/s (~1 GB/s) of continuous read I/O while Codex is running.

Interestingly, the measured throughput is very close to the bandwidth required for repeatedly processing an uncompressed 4K BGRA/RGBA frame at roughly 30 FPS:

3840 × 2160 × 4 bytes × 30 FPS ≈ 949 MiB/s

What steps can reproduce the bug?

Simply launching Codex Desktop causes severe system/UI stuttering on Windows 11, including noticeable mouse cursor stutter.

What is the expected behavior?

A hidden or disabled avatar/pet overlay should not continuously process/copy full-resolution frames.

Launching Codex should also not generate ~1 GB/s of continuous read I/O or cause system-wide mouse/UI stuttering.

Additional information

Investigation / suspected cause

The logs show that the newer Codex build creates an additional hidden window named:

avatarOverlay

Events also appear to be dispatched to both the main Codex window and this hidden overlay window.

Based on the measured ~974 MiB/s read throughput and the timing/size correlation, it appears that the hidden avatar/pet overlay may still be processing or copying full-resolution desktop/frame data at approximately 30 FPS even when the overlay is not visible.

I have not confirmed this from the Codex source code, so this is currently a suspected cause based on runtime measurements and logs.

Reproduction

1. Start Windows 11 normally.
2. Confirm that mouse/system responsiveness is normal.
3. Launch Codex Desktop.
4. Immediately observe significant mouse/UI stuttering.
5. Open the Codex pet/avatar feature.
6. Disable/close the pet feature.
7. The mouse/UI stuttering immediately disappears.

Start by reproducing the stutter on Windows 11 and comparing behavior before and after opening and closing the pet/avatar feature. Inspect logs and event activity around the hidden avatarOverlay window, then verify that launching Codex with the overlay hidden no longer causes continuous high read I/O or system-wide stuttering.