New NanoGPT Speedrun Record at 74.6s Achieved via Prefix Token Prediction

surmenok · x · 2026-08-03

Jan Varho set a new NanoGPT Speedrun world record at 74.6 seconds (−0.8s). The core innovation is the introduction of an auxiliary loss on prefix token prediction.

The mechanism works by giving partial credit during early training if the model predicts the longest token-prefix of the target token (e.g., predicting " banana" when the target is " bananas"). This approach can stack with Multi-Token Prediction (MTP), effectively reducing both training steps and overall time.

Related event: NanoGPT Training Speedrun Records Shattered, Hitting 74.6 Seconds(2 posts)→

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