Aaron Burnett
@aaronburnett · Sep 14, 2026
After the C+++ rewrite, our modeling indicated RL time for these models starting at 4.8 COULD be cut in half for ~2T models and substantially more time savings on a % basis for larger models. The thing I’d suggest watching is time between releases once they get some of the kinks
Elon Musk@elonmusk· Sep 14, 2026@itslueul Grok 4.7 should be roughly on par with Opus 5.0, not 5.1. Better in some ways, worse in others. We need to fix multimodal performance.
Grok 4.8 will be a noticeable improvement.
Grok 4.9 is probably Astra/Fable class.
Grok 5 maybe better than anything. We shall see.
Elon Musk
@elonmusk
Our training (aka pre-training) software is now the internally developed C/C++ stack, which was written primarily by the Starlink software team. This is awesome and probably best in industry.
However, our reinforcement learning stack is still somewhat of a legacy pile of many
02:07 PM · September 14, 2026 · 394.6K views
265
328
6.6K