Summary

  • Users on X are observing sharper outputs and extended response times from ChatGPT and Codex this week.
  • Many have noted significant advancements in web design and 3D video game outputs from ChatGPT.
  • While a formal announcement for GPT-5.6 is speculated for next week, OpenAI has not confirmed any plans yet.

Recent interactions with ChatGPT have sparked a wave of speculation among users, as many have reported noticeable differences in performance.

Over the past couple of days, testers on X have been sharing screenshots and timing their responses, leading to the theory that OpenAI might be conducting A/B tests of GPT-5.6 within ChatGPT, replacing some users' access to GPT-5.5 Pro.

Developer Anshu Chimala shared a video on Thursday illustrating a comparison between one-shot landing pages, stating, "Well well well, I'm one of the lucky ones with early GPT-5.6 Pro access."

Well well well, I'm one of the lucky ones with early GPT-5.6 Pro access!

One-shot pages from 5.5 Pro vs 5.6 Pro. Can you tell which is which? Looks like OpenAI's finally getting somewhere with design: pic.twitter.com/xghxmsANMG

— Anshu (@anshuc) June 19, 2026

Another developer, Dobroslav Radosavljevič, mentioned on X that the experience he has with Codex feels significantly different compared to the 5.5 model, with responses eliciting mixed reactions from users, some attributing it to placebo effects.

A prevalent observation among users is the increased response time. Conor Dart, one of the users amplifying these rumors, tested a one-prompt 3D browser game with physics and camera controls, which took over an hour to generate, contrasting sharply with GPT-5.5 Pro's usual 10-minute turnaround.

"Not perfect, but for a one-prompt AI game dev test, this is seriously impressive," Dart commented.

Possibly GPT-5.6 Pro inside ChatGPT using GPT 5.5 Pro....

I ran the same style of game build after testing GLM 5.2, and this honestly felt a lot smoother.

The full game took literally 60 minutes and 15 seconds to create. ( GPT 5.5 Pro always responded within a 10min mark)

A… pic.twitter.com/jfmcfJNab9

— Conor Dart (@Conor_D_Dart) June 18, 2026

AI expert Chetas Lua reported experiencing similar delays while testing a robotic simulation, suggesting his findings are linked to OpenAI's new model: “GPT 5.6 Pro continues to outperform [Anthropic’s Fable 5] in 3D tests,” he stated. Additionally, he noted response times reaching up to 20 or 40 minutes, a duration not observed since prior to the release of GPT-5.5.