Adding a loop to an already-trained model only paid off at 0.8B, and lost to a matched unlooped baseline
AspireAI community · arXiv (cs.LG, cs.AI)
Looping re-applies a block of layers so each token passes through it more than once, which is attractive because parameter count, disk size, memory footprint and training cost are unchanged. The catch is that every generated token pays for the loop: re-applying m of N layers makes each token about (N+m)/N times as expensive. This paper asks when a loop added after pretraining justifies that price, comparing a looped model against the same model trained identically without the loop and against the best unlooped use of the same inference FLOPs. Across Qwen3 and Qwen3.5 models from 0.8B to 9B parameters, only the looped 0.8B model beats both baselines; at 4B and 9B it does not beat the same model trained without the loop. The authors rule out benchmark saturation as the explanation, since on the same benchmarks the unlooped 9B model still scores up to 13 points higher than the 4B model.
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