Cohere's research director: pre-training ROI is slowing, focus shifts to test-time compute

sarahookr · x · 2026-09-02

Sara Hooker, Cohere's head of research, argues that pre-training ROI is slowing and the focus is shifting to test-time compute (TTC)—compute spent during inference/reasoning rather than training.

The compute profile needed for inference is very different: modern GPUs and TPUs are organized around maximizing matrix multiply performance and delivering data fast for throughput, both of which dominate deep neural networks—and both of these assumptions now change under TTC.

Related event: Sarah Hooker: Test-Time Compute and Agents Are Forcing an AI Infrastructure Rebuild(9 posts)→

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