Musk: Grok 4.9 likely Astra/Fable-class, Grok 5 'maybe better than anything'; RL time could be halved
nicolascraske · x · 2026-09-15
Elon Musk laid out the Grok roadmap on X: Grok 4.7 should be roughly on par with Opus 5.0 (better in some ways, worse in others, with multimodal performance still needing fixes); Grok 4.8 will be a noticeable improvement; Grok 4.9 is 'probably Astra/Fable class'; and Grok 5 'maybe better than anything.'
Quoted context from Aaron Burnett: after a C+++ rewrite, his modeling suggests RL training time for models from 4.8 onward could be cut roughly in half for 2T-parameter models, with larger percentage savings for bigger models. The key signal to watch is whether release cadence shortens once these kinks are fixed.
Related event: Musk maps Grok roadmap: 4.7 to match Opus 5.0, Grok 5 to lead everything(3 posts)→
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