The Inference Tax: How Prefix-Aware Routing Eliminates the Hidden Cost of LLMs at Scale

This article examines how LLM inference deployments waste compute through redundant prefill operations — recalculating identical prompt prefixes across requests. The authors explain how prefix caching combined with intelligent routing can reduce this waste, demonstrating that cache hit rates flip from approximately 25% under round-robin to 75% or more on workloads with shared prefixes. DigitalOcean’s prefix-aware routing gateway will soon extend these optimizations to its Serverless Inference platform for all users.