CSS hints
CSS performance hints in use: content-visibility, contain, will-change.
At a glance the headline numbers for CSS hints
CSS performance hints in use: content-visibility, contain, will-change.
12.4% of sites use CSS containment. content-visibility sits at 11.2%.
The CSS hints mix who uses what, and how fast each group loads
CSS hints. On the fleet: 32.5% will change, 29.4% aspect ratio, 14.5% scroll driven. 49.3% of sites use at least one will_change.
Why this matters for the Core Web Vitals, and where to start fixing it
These CSS properties limit how far a change can spread. contain declares a subtree self-contained, so a change inside it does not force layout outside it. content-visibility goes further and skips rendering offscreen sections until the visitor approaches them. will-change moves an animated element onto its own layer, so animating it does not repaint the rest of the page.
They attack the DOM problem directly: a big tree hurts because every change can touch all of it, and containment makes updates local. That is exactly what INP needs. will-change is the one to ration. Every promoted layer costs memory, and a blanket will-change makes performance worse, not better.
How does this affect the Core Web Vitals?
The choice barely moves the INP: 96% pass at best, 95% at worst. This signal does not separate passing sites from failing ones.
Chrome field data from 94,910 sites, representing millions of real page loads. How we measured.