Going headless does not automatically fix Core Web Vitals. It gives you better tools—if you use them.
- LCP — prioritize the hero image (modern formats, correct sizes, priority loading). Avoid shipping the entire media library to the client.
- INP — keep third-party scripts off the critical path; hydrate only interactive islands when you can.
- CLS — reserve space for images and embeds; do not inject late banners above content.
On the CMS side: oversized uploads, unbounded related-post queries, and plugin scripts that used to load in the theme will still hurt you if you mirror them into Next.js. Measure with field data (CrUX / Search Console) and lab tools, then fix the worst routes first.
If you are planning a cutover with performance as a goal, see Headless WordPress migration.
