LLM inference bottlenecks: weight loading gave way to KV reads as contexts grew

YouJiacheng · x · 2026-09-11

YouJiacheng argues speculative decoding doesn't change the nature of inference bottlenecks — the model and workload do: with short early contexts, weight loading dominated; long-context workloads shifted the bottleneck to KV cache reads.

A short but substantive note on how LLM serving performance limits evolve.

Related event: How LLM Inference Bottlenecks Evolved: From Weights to KV Reads to HBM Capacity(2 posts)→

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