CLS rarely comes from one page. It comes from one component used on all of them.
When a page jumps while it loads, the cause is almost always a shared component: an image without dimensions, a banner that pushes content down, a font that swaps late.
Fix it once
Reserve space in the component, not on the page. One change in the design system clears the shift everywhere it is used.
Fix the component, and a thousand pages get faster in the same deploy.
Takeaways
Give every media slot a size, load fonts with care, and never insert content above what people are already reading.
