ChatGPT Users Spot a Sneakier Squirrel: Same Pro Button, Supposedly Smarter Nuts 🥜

Users of OpenAI's ChatGPT spent the past two days posting screenshots and stopwatch readings on X, pointing to what they believe is an unannounced A/B test of GPT-5.6 Pro running inside the GPT-5.5 Pro selector. Developer Anshu Chimala published a side-by-side video on Thursday comparing one-shot landing pages and wrote: "Well well well, I'm one of the lucky ones with early GPT-5.6 Pro access." Developer Dobroslav Radosavljevič posted that what he's seeing inside Codex, OpenAI's coding agent, "feels waaaaaaaay different than [the] 5.5 model," with replies splitting between believers and skeptics calling it placebo.

The most consistent signal across the posts is speed. Conor Dart said a one-prompt 3D browser game with physics and camera controls took 60 minutes and 15 seconds to generate, compared with what he described as GPT-5.5 Pro's typical 10-minute run. "Not perfect, but for a one-prompt AI game dev test, this is seriously impressive," Dart wrote. AI insider Chetas Lua reported a similar slowdown on a robotic simulation, writing: "GPT 5.6 Pro continues to mog [Anthropic's Fable 5] in 3D test," and noting that response times stretched to 20 or 40 minutes, a pattern he said had not appeared since before GPT-5.5 shipped.

Not every comparison favored the rumored model. Chris, an AI benchmarker on X, said two models given the same spaceship-building prompt produced the suspected GPT-5.6 Pro output in 87 minutes against GPT-5.5 Extra High's 34 minutes and 42 seconds, while Anthropic's Fable 5 still produced better core geometry than either. "As I've said before, based on great authority, GPT-5.6 will be an incremental/solid improvement over GPT-5.5, not a Fable killer," he wrote, adding that he expects it to "trade blows with Fable 5 on some benchmarks, maybe win around half depending on the category, but not clearly surpass it overall." OpenAI has not confirmed the test or commented on the model version, and the posts remain informal user reports dated June 18, 2026.