Desktop app (Windows): runtime extraction after every update takes 15+ min at ~5 files/sec, looks like a hang

Title suggestion: Desktop app (Windows): runtime extraction after every update takes 15+ min at ~5 files/sec, looks like a hang

Environment:

• Windows 11 Home China 10.0.26200
• ChatGPT desktop (MSIX) v26.908.4834.0 (reproduced on v26.901 and v26.903 as well)

Symptom:

After every app update, the first launch shows no window for ~15 minutes. The process tree is alive and burning CPU, so it looks like a hang. Users (me included) assume it crashed and force-kill it — which restarts the copy from scratch on the next launch, making it look like an infinite hang loop.

Live diagnosis (v26.908, today):

• Monitoring %LOCALAPPDATA%\OpenAI\Codex\runtimes\cua_node\.staging-<hash>-<rand>\ during a "hung" launch shows the app re-copying ~4,700 files from the encrypted MSIX:
  • measured live: 2,436 → 2,486 files in 10s = 5.2 files/sec (~15 min total for 4,684 files)
  • app CPU clearly active during the copy (8.1 CPU-seconds in a 10s window)
  • small-file write benchmark on the same machine/disk: ~290 files/sec — so the bottleneck is not disk I/O
• After the copy finishes (~15 min), the app promotes the staging dir to the final hash dir, cleans up staging, and starts normally.
• Manually extracting app/resources/* from a downloaded plaintext MSIX into the target hash directory skips the copy entirely and the app starts in seconds — confirming the bottleneck is the per-file decrypt/copy of MSIX-encrypted resources, not antivirus or disk.

Impact:

Every user hits this on every update. The windowless 15-minute "hang" after updates reads as a crash, and force-killing makes it worse. This is very likely generating a steady stream of "app won't start" support load and uninstalls.

Suggestions:

1. Show a progress indicator (or any window) while extracting runtime files after an update
2. Cache/reuse unchanged files between versions instead of re-copying all ~4,700
3. Or ship runtimes as plaintext payload so no per-file decrypt is needed

Happy to provide logs if useful. This has reproduced consistently across the last 4 app updates.

No source file or test is named in the report. Begin by reproducing an update on Windows and tracing extraction into the runtime staging directory, using the reported ~4,700 files and 15-minute delay as a baseline. Done should address the windowless post-update startup experience and prevent active extraction from being mistaken for a hang.