SiteAud!tLint Support

Opportunity Performance

Large HTML (over 500 KB)

Severity
Opportunity
Impact
Medium
Effort to fix
Medium
Issue code
large_html

Why it matters

Heavy HTML takes longer to download and parse, especially on mobile connections.

How to fix it

Remove inline bloat such as embedded data, repeated markup and large inline scripts or styles.

What this means

The page's HTML is larger than 500 KB. This is the HTML document alone, not its images, scripts or stylesheets loaded separately. Typical content pages are well under 100 KB.

Why it matters

  • Slower first render. The browser has to download and parse the whole document before the page settles, which hurts mobile visitors most.
  • Crawling and indexing limits. Googlebot only processes the first 15 MB of an HTML file. Pages rarely reach that, but very large documents slow crawling and push important content further down.
  • A symptom of something else. Oversized HTML usually means data or code was put in the page that belongs elsewhere.

Common causes

  • Inline data. Frameworks such as Next.js and Nuxt embed the page's data as JSON for hydration. Category pages that pass every product's full record can reach megabytes.
  • Inline SVG icons repeated in every product card or menu item.
  • Inline CSS or base64 images written into the page instead of separate files.
  • Very long pages: all products on one category page, or every comment on one post.
  • Mega menus with hundreds of links repeated on every page.

How to fix it

  1. Open the page source and look at what takes up the space. A custom source search for __NEXT_DATA__, data:image or <svg shows which pages carry the same pattern.
  2. Pass only the fields the page displays to the framework's data layer.
  3. Move repeated SVG icons into a sprite and reference them with <use>.
  4. Paginate long lists, and load comments or reviews on demand.
  5. Turn on compression (gzip or Brotli). It reduces transfer size, though not the parsing work.

Verify the fix

Recrawl and compare. The issue's evidence shows each page's size, so you can see how much each change saved.

How it affects your score

Finding this issue on any page costs the Performance score 0.5 points, plus up to 4 more depending on the share of crawled pages affected. A smaller improvement with a modest effect on its own.

Find the affected URLs

Open Crawl > Issues and pick Large HTML (over 500 KB). Each affected URL is listed with its evidence, and Copy URLs or Export URLs hands the list to a developer. The issue also appears in the Action Plan, ranked by impact (medium) and effort (medium), and in the issues CSV under the code large_html. After fixing, run a new audit and use Compare to confirm the URLs moved to fixed.