How to diagnose and resolve page performance degradation issues caused by third-party script loading?

When page performance degrades due to the loading of third-party scripts (such as ads, analytics, or social plugins), professional tools can be used to diagnose and implement targeted optimization measures to resolve the issue. The diagnostic phase typically involves using browser developer tools (such as the Performance panel in Chrome DevTools) to record the loading process and identify scripts that block rendering or consume resources; Lighthouse or WebPageTest can generate performance reports, specifying script loading times, resource sizes, and impacts on key metrics (e.g., LCP, FID). Solutions can be approached from the following aspects: - Loading method optimization: Use the async (asynchronous loading) or defer (delayed execution) attributes for non-critical scripts to avoid blocking HTML parsing; - Resource streamlining: Remove unused redundant scripts and merge scripts with similar functions to reduce the number of requests; - Preconnection and caching: Establish connections to third-party domains in advance via `<link rel="preconnect">` and set reasonable caching policies (e.g., Cache-Control); - Conditional loading: Dynamically load scripts based on user behavior (e.g., triggered by scrolling) or device type (e.g., simplified loading for mobile devices). It is recommended to regularly use performance monitoring tools to track the impact of scripts and continuously optimize based on Real User Metrics (RUM), which can effectively improve page loading speed and user experience.