TECHNICAL ESSAYAI & ML

Speculative Decoding Explained: Achieving 3x LLM Inference Speedups

Draft models, verification steps, and hardware memory bandwidth optimization for low-latency AI assistants.

Dr. Sarah Chen
Dr. Sarah Chen
AI Research Scientist
·
Published on Aug 27, 2026
11 min read
Speculative Decoding Explained: Achieving 3x LLM Inference Speedups

Memory bandwidth is the primary bottleneck for autoregressive LLM decoding. Learn how draft models generate token candidates verified in parallel by the target model.

1. The Memory Bandwidth Bottleneck in Autoregressive LLMs

During standard autoregressive token generation, generating a single token requires loading all 70B parameter weights from GPU High Bandwidth Memory (HBM3) to SRAM. Because arithmetic intensity is low, the GPU tensor cores sit idle waiting for memory transfer.

Dr. Sarah Chen

Written by Dr. Sarah Chen

Focusing on speculative decoding, quantization, and real-time LLM inference pipelines.

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