Aurora and Core Web Vitals: How the Theme Affects Your PageSpeed Score
By Daniel Ekay
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May 18, 2026
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Core Web Vitals, specifically Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP), are Google ranking signals measured on every page. Aurora’s architecture addresses all three at the theme level, before any caching or optimisation plugin is involved. For the broader SEO picture, see the SEO overview.
Largest Contentful Paint (LCP)
LCP measures how long it takes for the largest visible element on the page to load. Aurora contributes to a fast LCP through how Aurora loads CSS:
- Conditional CSS loading: only the stylesheet for the active layout is loaded. No unused CSS from other layouts is shipped to the visitor.
- No render-blocking scripts: Aurora’s layouts render as pure HTML server-side. No JavaScript is required to display the layout.
- Lightweight HTML output: no builder-generated wrapper divs or inline styles adding to the document size.
Cumulative Layout Shift (CLS)
CLS measures unexpected movement of page elements as the page loads. Aurora produces low CLS because:
- Layouts are rendered server-side. There is no client-side reflow as JavaScript builds the page.
- Image dimensions are preserved in the HTML output so the browser reserves space before images load.
- No third-party builder scripts inject or reposition elements after the initial paint.
Interaction to Next Paint (INP)
INP measures how quickly the page responds to user interactions. Aurora ships minimal JavaScript: only what is needed for interactive features like the mobile menu, sticky header, and load more button. There is no global builder framework executing on every page.
What Aurora Does Not Control
Theme architecture is one factor in PageSpeed scores. The following are outside Aurora’s control and should be addressed separately:
- Hosting speed: server response time (TTFB) is determined by your host
- Image optimisation: compress and properly size images before uploading
- Caching: a caching plugin or CDN significantly improves repeat visit performance
- Third-party scripts: analytics, ads, and chat widgets add weight Aurora cannot remove