OpenAI has launched GPT-5.4 Mini, providing free ChatGPT users with a significant speed upgrade. This model is reported to be over twice as fast as previous versions while maintaining similar high-level capabilities, according to OpenAI's blog announcement. The new "subagent" functionality enhances efficiency by enabling multitasking, allowing the AI to breakdown complex tasks. Both GPT-5.4 Mini and the smaller GPT-5.4 Nano are designed for low-latency applications, fundamentally changing AI workflows.