GPT-5.5 Fast is severely throttled: slower than 1/20 of Standard even after multiple app restarts

Codex app version

Desktop Codex: 26.608.12217 — released Jun 8, 2026

Platform / plan

• macOS Tahoe 26.5.1
• Apple Silicon MacBook Pro
• Pro plan
• Mode: GPT-5.5 Fast

Related feedback ID

019eb48b-00d0-7b91-b50a-cbd119bb5c4c

Summary

GPT-5.5 Fast is currently experiencing a severe speed degradation. The actual response and task progress speed feels slower than 1/20 of Standard mode, even though Fast mode consumes higher usage.

I have restarted the Codex app multiple times, but the speed did not improve at all. This does not look like a temporary UI glitch or local app state issue.

Observed behavior

• GPT-5.5 Fast is extremely slow.
• The speed is far below what Fast mode should provide.
• In practice, it feels slower than even 1/20 of Standard mode.
• Restarting the Codex app multiple times does not fix the issue.
• The degraded speed makes normal task execution extremely inefficient.

Expected behavior

GPT-5.5 Fast should be meaningfully faster than Standard mode, especially because it consumes higher usage. If Fast mode is degraded, throttled, or affected by backend capacity issues, the product should clearly communicate that to users.

Actual behavior

Fast mode currently consumes Fast-mode usage but delivers a speed that feels dramatically slower than Standard. The issue persists even after restarting Codex multiple times.

Why this matters

This is a serious usability and fairness problem. Users choose Fast mode because they need faster task completion and accept the higher usage cost. If Fast mode becomes slower than Standard while still charging higher usage, the weekly limit is wasted very quickly without receiving the expected performance.

For Pro users, this makes the 20x weekly usage limit much less useful, because tasks consume expensive Fast-mode quota while progressing extremely slowly.

Request

Please urgently investigate whether GPT-5.5 Fast is currently affected by throttling, backend latency, routing issues, or a performance regression.

If Fast mode is temporarily degraded, please make that visible in the UI and consider crediting back the wasted Fast-mode usage for affected users.

https://github.com/user-attachments/assets/cddebe8a-1442-4624-9463-0b8ff7ea8746