Stop Wasting Tokens: High-Performance Local Re-ranking with Spring AI and JEP 489 RAG latency is killing your UX because you’re still piping re-ranking tasks to overpriced LLM APIs. In 2026, if you aren’t running SIMD-accelerated Cross-Encoders locally on your JVM to prune your context window, you’re burning money and adding 500ms of unnecessary overhead. Why Most Developers Get This Wrong API Hopping: Sending 50 retrieved chunks back to a remote LLM for "ranking" is a performance nightmare and a massive security surface area. The "For-Loop" Trap: Implementing similarity scoring with standard Java loops instead of leveraging JEP 489 (Vector API), missing out on 8x-16x hardware speedups. Ignoring Observation: Flying blind without the Spring AI Observation API, failing to realize that 80% of their RAG "intelligence" is actually lost in the noise of poor retrieval ranking.…