SegmentMuse answers
Should personalization swap the hero image?
Only if it decides before the page is sent. Swapping the hero in the browser delays the largest image, which slows Largest Contentful Paint.
Why a late swap hurts
web.dev notes that images managed by JavaScript rather than present in the initial HTML cannot be found early. The browser waits, then downloads the new hero. Your main image arrives late.
What to do instead
Pick the hero on the server or at the edge, and put it in the HTML. If you cannot decide in time, show the default hero and personalize smaller blocks below it.
Source
web.dev, Optimize Largest Contentful Paint. Reviewed Sep 23, 2026.