React applications can experience performance issues due to factors like slow component mounts and unnecessary render cycles, but various tools and techniques, including those built into React, are available to diagnose and improve performance. The performance timeline feature introduced in React 15.4.0 allows developers to visualize component lifecycles and understand timing on methods like [componentDidMount] and [render], although it currently only works in Chrome, Edge, and IE. While this feature is useful for local development, it does not function in production builds. For analyzing performance issues in production, tools like LogRocket offer comprehensive insights by recording performance timings, user interactions, and more, helping developers understand and address problems. The series also includes interactive demos, such as an intentionally performance-degraded version of the TodoMVC app, to help users identify performance bottlenecks.