As Large Language Model (LLM) systems become more complex, ensuring their high performance, reliability, and efficiency necessitates advanced observability, feedback, and testing strategies. Observability plays a crucial role in identifying and resolving latency bottlenecks and enhancing performance by providing real-time insights into application behavior. Developers can optimize LLM systems by leveraging enriched observability data, which includes metadata like user IDs and operational metrics, to drive meaningful optimizations. Collecting feedback through methods such as explicit and implicit user feedback, human annotation, and automated evaluations enables continuous improvement, while testing with "golden data" ensures accuracy and reliability. These practices collectively help developers transform complex LLM systems into robust and high-performing applications, effectively balancing quality, cost-efficiency, and latency.