速度
DOM サイズ
重要な理由
Every element costs memory, style calculation and layout time. Pages with thousands of elements respond slowly to taps and clicks (Interaction to Next Paint) and render slowly on phones.
修正方法
- Remove hidden duplicate markup, such as separate mobile and desktop menus.
- Paginate or lazy-render long lists, comments and product grids.
- Flatten deeply nested wrapper elements produced by page builders.
次のツールで確認
- Page Speed Test – Lighthouse performance score, lab metrics and real-user Core Web Vitals for any page.
- Core Web Vitals Checker – Check real-user LCP, INP and CLS from the Chrome UX Report for a page and its whole site.
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