How to optimize the first screen loading speed for Single Page Applications (SPAs)?
When optimizing the first-screen loading speed of a Single-Page Application (SPA), focus on resource loading efficiency and rendering priority, and achieve improvements by reducing the initial loading volume, optimizing the loading order, and increasing rendering speed. Resource volume control: Use code splitting (such as Webpack's dynamic import) to split non-first-screen code and only load initially necessary modules; compress images (using WebP/AVIF formats) and implement lazy loading to reduce the weight of first-screen resources. Loading order optimization: Use preload for critical CSS/JS to preload, and defer/async for non-critical resources to delay loading; use CDN to distribute static resources and shorten network request paths. Rendering mechanism adjustment: Combine Server-Side Rendering (SSR) or Static Site Generation (SSG) to output first-screen HTML, reducing client-side JavaScript rendering pressure; optimize first-screen JS execution logic to avoid long tasks blocking rendering. Lighthouse can be used to detect first-screen loading bottlenecks, prioritize optimizing the LCP (Largest Contentful Paint) metric, and continuously monitor the actual improvement effect of code splitting and resource compression on loading speed.
