Optimizing web page performance is complex, often hindered by the limitations of existing tools that provide descriptive but not explanatory insights into page loading events. This challenge is addressed by Replay's innovative approach, which introduces the concept of "limiting paths" to identify the sequence of events that must occur before a page loads or responds to user input. By focusing on these paths, developers can optimize critical events and ignore irrelevant ones, thus simplifying the identification and resolution of performance regressions. This method is particularly valuable for React applications, which involve implicit and asynchronous behaviors difficult to interpret and optimize. An example discussed is a regression caused by an extra network call in Replay’s devtools that blocks page loading, a problem not easily discernible using traditional network waterfall charts. Replay's performance analysis computes limiting paths to highlight such regressions, ensuring precise identification of meaningful performance issues without false positives or negatives. Additionally, the methodology enables detailed analysis of both network requests and main thread computations, providing developers with insights into React’s performance characteristics and aiding in the construction of high-performance applications. Replay's performance analysis tool is set to enter closed beta, offering a more efficient avenue for optimizing web pages and React applications.