首屏渲染优化终极指南：从5秒到0.5秒的魔法实践 ✨

// 示例：通过PerformanceObserver监控
PerformanceObserver observer = new PerformanceObserver((list) -> {
    for (PerformanceEntry entry : list.getEntries()) {
        if (entry.getName().equals("first-contentful-paint")) {
            System.out.println("FCP: " + entry.startTime + "ms");
        }
    }
});
observer.observe({type: 'paint', buffered: true});

graph LR
A[浏览器] -->|HTTP/2| B(CDN边缘节点)
B -->|QUIC协议| C[源站服务器]
C -->|Brotli压缩| D[OSS存储]

graph TD
A{是否需要动态数据} -->|是| B[SSR]
A -->|否| C{内容更新频率}
C -->|高频| D[SSR+ISR]
C -->|低频| E[SSG+定时重建]

// 基于EdgeRoutine的边缘渲染示例
export default async function handleRequest(req) {
  const SSRContent = await fetch('https://api.yoursite.com/ssr', {
    backend: "origin_server",
    cacheTtl: 300 // 5分钟边缘缓存
  });
  
  return new HTMLRewriter()
    .on('img', new LazyLoader()) // 图片懒加载组件
    .transform(SSRContent);
}

<link rel="preload" href="hero-image.webp" as="image" 
      media="(min-width: 768px)" importance="high">

// React动态加载示例
const PaymentModule = React.lazy(() => 
  import(/* webpackPrefetch: true */ './Payment')
  .then(module => ({ default: module.Payment }))
);

graph LR
A[真实用户] --> B{埋点类型}
B -->|Navigation Timing| C[FCP/LCP]
B -->|Performance Observer| D[CLS]
B -->|自定义埋点| E[业务关键模块]

// 异常捕获示例（Java版）
public void monitorLCP() {
    PerformanceMonitor.onLargestContentfulPaint(entry -> {
        if (entry.startTime > 2500) { // 超过2.5秒触发报警
            TencentCloudAPM.report("LCP超限", Map.of(
                "duration", entry.startTime,
                "element", entry.elementTag
            ));
        }
    });
}

// A/B测试数据样例
OptimizationReport report = new ReportBuilder()
    .metric("FCP").before(5200).after(1800).improvement(65%)
    .metric("LCP").before(7300).after(2100).improvement(71%)
    .build();