GPT-5.4 is unresponsive on first prompt, but starts working after switching to 5.3 Codex and back #16870

Description

I’m seeing a strange issue with GPT-5.4.

In a fresh session, when I send the very first message to GPT-5.4, it often takes a very long time to react. It looks almost like it is stuck and not even starting to think.

But if I switch to 5.3 Codex, that model reacts immediately. Then if I interrupt it and switch back to GPT-5.4, GPT-5.4 starts working fine.

So the workaround right now is:

• start with GPT-5.4 → slow / unresponsive

• switch to 5.3 Codex → instant reaction

• interrupt and switch back to GPT-5.4 → now it works

This makes me suspect there is some initialization issue with GPT-5.4 on the first request.

Plugins

openai plus

OpenCode version

1.2.24

Steps to reproduce

Repro

• Open a fresh session
• Select GPT-5.4
• Send the first message
• Wait and observe slow / no response
• Switch to 5.3 Codex
• Observe that it reacts immediately
• Interrupt it
• Switch back to GPT-5.4
• Observe GPT-5.4 now works normally

Screenshot and/or share link

No response

Operating System

macos m1

Terminal

No response