5 LLM APIs Tested for Latency: Real Data [2026]

Originally published at kunalganglani.com — read it there for inline code, hero image, and live links. 597 milliseconds. That's how long Claude Haiku 4.5 takes to deliver its first token on a medium-length prompt. GPT-4.1 Mini? Roughly 2,400ms. Four times slower. That gap is the difference between an app that feels alive and one that feels broken. I tested five LLM APIs for latency — Claude Haiku 4.5, Claude Sonnet 4, GPT-4.1, GPT-4.1 Mini, and Gemini 2.5 Flash — across time-to-first-token (TT...