How to optimize the first screen display speed of a page by preloading resources?

When optimizing the first screen display speed of a page, preloading critical resources is an effective method. By preloading core resources necessary for the first screen (such as critical CSS, first-screen images, and core JS), resource request delays are reduced, thereby accelerating first-screen rendering. During implementation, it is first necessary to identify first-screen critical resources through performance analysis tools (such as Lighthouse) to distinguish between essential and non-essential resources. For critical resources, the `<link rel="preload">` tag can be used to specify the resource URL, type (e.g., as="style" or as="image"), and priority to ensure the browser loads them first. For example, the main first-screen image or core CSS files are suitable for preloading, while non-first-screen images or secondary JS do not need to be preloaded to avoid occupying bandwidth. It is recommended to adjust the preloading strategy according to actual scenarios to avoid resource waste caused by excessive preloading; at the same time, monitor loading performance and further improve first-screen speed by optimizing resource size (such as compressing images and精简CSS). This is a practical step for first-screen loading optimization.