Two different tricks for fast LLM inference

Anthropic's fast mode offers 2.5x faster token generation using low-batch-size inference with their full Opus 4.6 model. OpenAI's fast mode provides 15x faster speeds using Cerebras chips but with a less capable distilled model called GPT-5.3-Codex-Spark. Both companies have implemented different technical approaches to accelerate LLM inference.