Does disabling autoplay on my videos impact page performance?

Yes. Marginally.

If the hero/background video is still requested on initial page load (for example because it is in the hero and must appear straight away), turning autoplay off mainly changes the user experience, not the network cost or Core Web Vitals like LCP.​

To actually improve speed, you need to optimise the asset and loading strategy: shorter, well‑compressed video, modern formats, and a light hero/poster image as the first thing rendered.​

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