Bandwidth-Bound Decode Throughput

Because decode reads every weight once per step, its speed is a division: memory bandwidth over bytes per step. That one formula gives single-stream tokens per second for any model on any card, the batch curve that flattens at the ridge point, the effect of quantization, and the point where the KV cache rather than the weights becomes the thing being read. This page derives it, works it for a 70B model on four accelerators, and shows how to read a vendor throughput claim against it.