Prompt Caching for RAG Pipelines 2026: Anthropic & vLLM
Prompt caching for RAG pipelines is table stakes in 2026: learn how Anthropic and vLLM cache prefixes to cut cost and latency in long-context retrieval systems.
Chapter 1: Why Prompt Caching Became the Default for RAG in 2026 If you are building a retrieval-augmented generation pipeline today and you are not caching your prompt prefixes, you are paying a tax that your competitors stopped paying eighteen months ago. That is not hyperbole. It is arithmetic. Prompt caching went from a clever optimization to table stakes because the economics of long-context RAG made it impossible to ignore, and because both the major API providers and the open-source serving stack shipped implementations mature enough to build on. This chapter explains how we got here: what changed in retrieval...