Understanding React Performance Patterns Developers Often Get Wrong

Modern React applications benefit from powerful tooling, compilers, and frameworks, yet many teams still experience performance regressions that are hard to reason about. These issues rarely come from obvious mistakes. Instead, they emerge from small, well-intentioned patterns that quietly compound as applications grow. This session focuses on building a correct mental model of how React actually renders and re-runs logic, especially in applications that have been in production for months. We will explore common performance traps around hooks, dependency arrays, memoization, and state updates that frequently appear in real-world codebases. Rather than theoretical explanations, the talk uses simplified, practical examples to show why patterns like useEffect, useMemo, and useCallback sometimes behave differently than expected, how stale closures occur, and how render cascades start. Attendees will also learn how to use profiling tools to identify meaningful performance issues instead of guessing or over-optimizing. This talk is intended for and relevant to modern React applications, including those using the latest features and compilers.