Elyse Betters Picaro / ZDNETFollow ZDNET: Add us as a preferred source on Google.ZDNET's key takeawaysGPT-5.4 mini runs more than twice as fast as GPT-5 mini.New models aim at agents, coding, and multi-modal workflows.Developers can mix large planning models with cheaper subagents.Over the past few weeks, we have seen the generation of OpenAI's flagship large language models iterate from GPT-5.3 to GPT-5.4. Think of the model as the engine that powers AI computation. Each generational jump usual...