As SEO experience shows, having a video has a very good effect on the time that users spend on pages. And beautiful pictures make viewing more pleasant. But this should not negatively affect the download speed of the content.
It is implemented with the addition of an inline transparent image of the same size, so that when loading there are no “jumps” of elements, which has a positive effect on the Cumulative indicator Layout Shift (CLS). The approach itself mainly affects Largest Contentful Paint (LCP) and First Contentful Paint (FCP).
- Lazy loading videos and frames
It is very important for optimization because frames (especially video) immediately load a large number of scripts, which immediately significantly reduces the speed indicator down by about 25-30 points, affecting all indicators, except perhaps Cumulative Layout Shift (CLS). It’s implemented in such a way that the injection of a replaceable quick block does not break the markup of the original page, unlike other plugins. Also, the replacement block itself, containing the video preview picture, is also loaded via the lazy loading of images described above.
- Embedding small images
By default, images less than 2KB are embedded in HTML and CSS. This makes loading them as fast as possible. Configurable here.