TL;DR: SmartVideo loads asynchronously and ships no third-party ad code by default. In our Lighthouse benchmark, a blog page with SmartVideo weighed about half as much as the same page with a YouTube embed and at least 15% less than with a Vimeo embed, with fewer requests than either.
Other video players are often filled with bloat, like ad code and “related video” mechanisms. In our benchmark, the YouTube embed loaded Google’s doubleclick.net ad-tracking domains; the SmartVideo page loaded none of them.
The SmartVideo player uses a lightweight async loader with no third-party ad code by default, allowing the rest of your page to load while the script downloads.
To keep your layout steady, reserve the video’s space in your CSS so the player has room before it appears. A <smartvideo> tag has no size of its own until the player script runs. Our WordPress plugin (version 2.3 and later) reserves a 16:9 box for responsive videos, which is the default. On other sites, add smartvideo { display: block; aspect-ratio: 16 / 9; }, using your video’s shape. Learn more about Core Web Vitals.