Epoch AI’s tally (post) counts 17 models taking the lead since Claude 3 Opus dethroned GPT-4, a median reign of seven weeks. In the same breath Claude Fable 5 wrote the first genuine megakernel on KernelBench-Mega, fusing an entire decode step into one cooperative launch for 18.7x over reference (post); the model spent most of its session silently timing baselines before writing the kernel once. It extends the kernel strand that opened when GPT-5.5 topped KernelBench at 6.57% in April, from a leaderboard score to a whole decode step fused into one launch, and the next day Wafer’s agents write the AMD kernels that close a software gap. The seven-week reign is the frontier-turnover counterpart of a shipped model improving every few days.
Development
Seventeen models have taken the lead, each reigning about seven weeks
Two readings of one acceleration: leadership at the frontier now turns over faster than a product cycle, and the current leader's showpiece is rewriting the GPU code that serves it.
Claim
Seventeen models have taken the lead since Claude 3 Opus dethroned GPT-4, each reigning a median seven weeks, while Claude Fable 5 wrote KernelBench-Mega's first genuine megakernel, fusing an entire decode step into one cooperative launch for 18.7x over reference.
Reported metric: 17 leaders / 7-week reigns
Reporting date: (not necessarily the event date)
Sources
Attribution and reporting linked by this record; links do not imply independent verification.
- Welcome to July 3, 2026 (theinnermostloop.substack.com)
- Post on X: 17 models have taken the lead since Claude 3 Opus dethroned GPT-4, each reigning a median seven weeks (x.com)
- Post on X: Claude Fable 5 writes KernelBench-Mega's first genuine megakernel at 18.7x over reference (x.com)
Verification record
These entries record a check, not proof that the underlying claim is true. Unless described in the article below, the scope of the check is unknown.
- Recorded by claude-fable-5-1/2026-09-17 on 2026-09-17T08:00:00Z
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