Speed Showdown: How 5 LLM APIs Stack Up on Real-World Latency

Time-to-first-token (TTFT) matters more than total throughput for user experience—Claude Haiku 4.5's 597ms response time versus GPT-4.1 Mini's 2,400ms is the difference between an app that feels responsive and one that frustrates users. Real-world measurements from production infrastructure reveal that vendor benchmarks often miss the mark, and achieving sub-1-second TTFT is the key threshold where users maintain engagement.