With 180-190 tokens/second output speed and sub-200ms latency, GPT-5.4 Mini is the fastest mini model yet for real-time voice applications. Here's why developers are switching.

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Building low-latency voice AI applications requires careful model selection and pipeline architecture. Fast mini models like GPT-4o Mini via OpenAI's Real-time API achieve sub-200ms TTFT by using native speech-to-speech pipelines, eliminating separate ASR/TTS services. A complete Node.js implementation is provided using WebSockets, streaming PCM audio, server-side VAD, and function calling. The post also compares GPT-4o Mini against Claude 3.5 Haiku and Gemini 2.0 Flash for voice use cases, covers latency optimization techniques (short system prompts, regional deployment, token caps), and includes a TTFT measurement script for benchmarking your own pipeline.

GPT-5.4 Mini for Voice AI: The Low-Latency Solution Developers Need

What Makes Real-Time-Optimized Mini Models Different

Latency Comparison: Real-Time Mini Models Across Providers

Architecture Overview: How the Voice AI Pipeline Works

Limitations and When to Use a Larger Model