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GPT-5.5 Fast suddenly feels as slow as Standard, with long thinking/context/search stalls #24422
Description
Summary
Over the past two days, GPT-5.5 Fast in Codex has felt significantly slower than before. It now feels closer to the usual Standard speed rather than Fast.
Some simple tasks that would normally complete quickly are now taking 10–20+ minutes, and sometimes even longer, before the task finishes. This feels like a clear regression compared with the previous normal behavior.
What I am observing
- GPT-5.5 Fast feels noticeably slower than it did before.
- Simple tasks can take 10–20+ minutes or longer to complete.
- The “thinking” phase can get stuck for 40+ seconds, sometimes around a minute or more.
- Automatic context compression also appears to take a very long time.
- Reading and searching steps are also extremely slow.
- At the same time, GPT-5.5 Fast also seems less capable / less reliable than before, so the experience feels both slower and less effective.
Why I do not think this is just my local machine or network
I do not believe this is caused by my computer performance. I am using a high-end MacBook Pro configuration:
- MacBook Pro 16-inch
- Apple M5 Max
- 128 GB memory
- macOS Tahoe 26.5
- Codex version 26.519.41501 (3044)
I also do not believe this is simply a network speed issue, because the slowdown is specifically noticeable in Codex/GPT-5.5 Fast behavior and is very different from how it normally performed before.
Expected behavior
GPT-5.5 Fast should feel meaningfully faster than Standard, especially on simple tasks. Thinking, context compression, reading, and searching should not regularly stall for long periods on basic requests.
Actual behavior
GPT-5.5 Fast currently feels like Standard speed or worse, with long stalls during thinking, automatic context compression, reading, and searching.
Request
Could the team please check whether there has been a recent performance regression, routing change, capacity issue, or other backend/client issue affecting GPT-5.5 Fast in Codex?
I am also curious whether other users are seeing the same thing, because this slowdown feels very obvious compared with the previous normal GPT-5.5 Fast experience.
Activity
github-actions commentedon May 25, 2026
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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GGBondBlueWhale commentedon May 25, 2026
Additional context: I am posting the recent Feedback IDs from several affected Codex conversations. I hope these can help the team locate, compare, and optimize the recent slowdown/regression more quickly.
Feedback IDs:
019e5df0-cb41-7e93-b0bb-b18658e9241d019e5e2b-2f3d-79f1-aa7a-01c8a2825f13019e5aa5-d5c9-7e02-8326-7ebdfea880de019e5bb8-e7fe-7ea1-975c-a461a6eb18c1019e5bbc-bf97-73e3-817b-042febe97482019e5bdf-2b3a-78e1-995c-008444cb5558019e5d7d-5ef0-7942-a913-18ac86391836019e5df8-6b4f-79d2-b05d-a79e11c0fc6d019e5e43-53fb-7543-b760-7611aec7de9bSome of these were from recent simple tasks where GPT-5.5 Fast felt unusually slow, including long stalls during thinking, automatic context compression, reading, or searching.
hungho66 commentedon May 25, 2026
Yes, I have the same problems.
ThinhDangDev commentedon May 25, 2026
same problem
zjcanjux commentedon May 25, 2026
same problem
xiaobc1234 commentedon May 25, 2026
same problem
Coreatom commentedon May 25, 2026
same problem
AndrewXiGua commentedon May 25, 2026
same problem
MythicalFish commentedon May 25, 2026
Yup, same
hhllnw commentedon May 25, 2026
same problem
12 remaining items
daoseng33 commentedon May 26, 2026
Same, and make $100 10x credits plz.
godson594 commentedon May 27, 2026
Same problem, I thought I was going crazy. Reddit is filled with threads like this too.
starwu40 commentedon May 27, 2026
same problem
L3monJuic3 commentedon May 27, 2026
Same problem
JC-S commentedon May 27, 2026
#24431 (comment)
Guys you may take a look at my thoughts on the possible root cause of this issue. If you have the environment available, you may also try the approach I suggested.
w2jmoe commentedon May 27, 2026
jorgenuanzs commentedon May 27, 2026
Same problem, until sunday May 24th works great and monday the speed dramatically decreased. I'm working with 5.4 in the meantime.
ilijasam commentedon May 27, 2026
Same problem. This becomes quickly problematic for people working with knowledge work and planning projects based on codex performance.
sybershocknetworks commentedon May 28, 2026
Same problem - A small a module rework is taking more than an hour to complete. :(
newideas99 commentedon May 28, 2026
also seeing this
oliverbj commentedon Jun 3, 2026
Same problem for me.
newideas99 commentedon Jun 3, 2026
This feels fixed to me, how is everyone else feeling?
etraut-openai commentedon Jun 3, 2026
We had a capacity issue last week that resulted in slow responses for some uses. We have mitigated the issue. I'm going to close and lock this issue. If you arrive here in the future because you're experiencing slow performance, look for a recent active issue or open a new one.