Automatic Lazy Rendering (ALR)
This is a feature in the WP Rocket caching plugin that prevents the browser from rendering parts of a page that are not visible when the page is first loaded (below the fold) until the visitor scrolls down to those areas. The goal is to improve page speed.
Technically, WP Rocket uses the CSS property “content-visibility: auto” on the affected sections, identified by the attribute “data-wpr-lazyrender="1"“, if you look at the source code.
When the page first loads, the browser skips calculating the layout and rendering for the invisible portion of the page. This improves metrics such as “Total Blocking Time” and “Interaction to Next Paint.”.
This feature is enabled by default and does not have a toggle in the settings.
Side effect: Because sections that haven't been rendered yet only have an estimated height, jump marks such as Anchor Links end up in the wrong place and cause scroll animations to get out of sync. This can be remedied by using exceptions via filters or by disabling the feature via code.
add_filter( 'rocket_lrc_optimization', '__return_false', 999 );