This half-day tutorial on Software Performance Engineering for AI-powered Software (AIware) will equip practitioners and researchers with the frameworks, techniques and hands-on insights needed to transform impressive FM/LLM demos into production-ready systems. We will survey transformer decoding fundamentals and model-serving best practices, expose end-to-end performance engineering challenges across the FMware lifecycle, introduce advanced methods such as real-time adaptive routing, and work through a concrete SLA-awareness case study for AI-assisted coding. Participants will leave with actionable patterns and recommendations validated in industrial deployments. The session draws on the presenters’ extensive experience working with FMware systems in both research and real-world settings and prior tutorials at ICSE, FSE and ASE.