Why your AI-built site is slow (it's almost always images and bundles)

Who this is for: Founders who want a faster site without rebuilding it from scratch.

The page can look lightweight while shipping oversized hero images, unused generated components, animation libraries, font weight, and scripts that mobile users pay for before seeing the offer.

Prompt-driven iteration makes it easy to add sections and assets without deleting the earlier experiments from the final build.

Slow pages make every other improvement harder to notice. Buyers cannot trust, read, or act on a page that is still arriving.

Start with this diagnosis

The target query for this guide is AI-built sites that feel heavy on mobile despite looking simple.. That matters because a good fix should match the real search or buyer problem, not a generic SEO scorecard. Treat this as a launch-readiness pass: find the blocker, fix the smallest useful thing, publish, then verify from the live URL.

For AI-built sites, the visible design often gets ahead of the operational details. The homepage might look polished while the browser title is generic, the canonical points at the wrong host, the images are heavier than they need to be, or the copy avoids the facts a buyer needs. That is why the checks below are ordered from technical blockers to trust and persuasion.

What to check, in order

1. Start with the largest above-the-fold image and confirm its displayed size matches its file size.
2. Remove unused generated sections, carousels, animations, and scripts.
3. Set width and height on images and embeds to reduce layout shift.
4. Lazy-load media below the first screen.
5. Use modern formats and compression for decorative images.
6. Re-test on mobile after each batch rather than guessing from desktop.

Do not skip the order. If Google cannot crawl the final URL, a better description will not help. If buyers cannot verify the business, a faster hero image will not earn trust. If the copy is generic, a new animation will not make the offer more credible.

What not to do

• Do not replace every image with blurry placeholders that hurt trust.
• Do not optimise a hidden gallery before the hero and main CTA.
• Do not add another performance plugin before deleting obvious weight.

The point is not to make the site bigger. The point is to remove confusion. Most AI-built sites improve fastest when you preserve the useful parts of the generated design and replace vague defaults with exact settings, real proof and clearer next actions.

A 20-minute workflow

Start with the live production URL and write down what you expect a stranger to understand in the first screen: the audience, the problem, the offer, the proof, and the next action. Then compare that expectation with what the page actually exposes to a crawler, a keyboard user, and a skeptical buyer. This keeps the work grounded in evidence instead of taste.

Spend the first five minutes on access and indexability. The page should load without a preview token, return a normal success status, avoid noindex directives, and point canonical signals at the same URL you want people to share. Spend the next five minutes on metadata and page structure: title, description, H1, headings, internal links, and whether the important copy is real text rather than only visual decoration.

Use the next five minutes for trust and action. Look for the contact path, policy links, business context, proof you can stand behind, and the form or CTA state after a visitor clicks. Use the final five minutes for mobile speed and accessibility basics. That order is deliberately boring, because boring checks catch the problems that make a finished-looking AI-built site underperform.

1. Check the exact live URL, including host, protocol and path.
2. Confirm the page explains ai-built sites that feel heavy on mobile despite looking simple. in visible, crawlable copy.
3. Fix one blocker at a time instead of asking the builder for a full redesign.
4. Publish the smallest safe change and verify it outside the editor.
5. Keep a short change log so future prompts do not undo the fix.

How to brief the builder

A good builder prompt names the page, the constraint and the proof boundary. Do not ask for better SEO in the abstract. Ask for the exact output you need: the metadata fields, redirect behavior, accessible labels, image sizes, footer links, form states or copy changes. Include the instruction to keep existing URLs unless a URL itself is the problem.

For founders who want a faster site without rebuilding it from scratch., the safest wording is usually: keep the current visual direction, change only the launch-readiness issues, and show the before/after evidence. That prevents the tool from replacing a working layout with a new generic one. It also keeps the conversation focused on the business risk rather than a fresh design pass.

Be especially firm about proof. If a page needs a testimonial, customer result, office address, certification or measured performance claim, supply the real detail yourself. If you do not have it yet, ask the builder to write around the gap honestly. Specificity beats fake confidence. A smaller true claim is stronger than a dramatic claim a buyer cannot verify.

How to verify after publishing

Verification should happen on the published URL, not inside the builder preview. Open the page in a private window, inspect the source or rendered DOM where relevant, and run the same checks again. If the fix was metadata, compare the title, description, canonical and social URL. If it was accessibility, tab through the page and check labels. If it was speed, test mobile and look at the largest visible assets first.

Do not expect every external tool to update instantly. Search Console, snippets and social previews can lag behind the published change. What you can verify immediately is whether the live page now serves the right evidence. Once the page is technically clean, request indexing or resubmit a sitemap only where that makes sense.

Concrete example

The boring image attributes still matter.

<img
  src="/images/shopify-bookkeeping-dashboard.webp"
  alt="Monthly Shopify bookkeeping dashboard"
  width="1200"
  height="675"
  loading="eager"
  decoding="async"
/>

Use examples like this as a pattern, not a claim to copy. Replace every business name, page promise, audience and proof point with your own real details. If you do not have proof yet, say less and be clearer rather than manufacturing confidence.

Builder-specific notes

• Lovable, v0, and Bolt projects often need asset cleanup in generated code.
• Framer and Webflow pages need image sizing and animation restraint.
• Wix, Durable, and 10Web sites often need media-library cleanup before layout changes.

After each change, test the production URL rather than trusting the editor preview. Preview pages are useful while building; Google, buyers and accessibility tools interact with the published page.

Copy-paste fix prompt

Paste this into your builder or hand it to whoever owns the site. Keep the constraints in place, especially the instruction not to invent proof.

Speed-audit my AI-built site. Find oversized images, unused generated sections, heavy scripts, animation libraries, layout shifts, and fonts that slow the first screen. Keep the design intent. Compress and resize images, defer below-the-fold media, remove unused components, and list every change with a before/after verification step.

Scan it before and after

Run the page through Clunky AI's free scan before the fix and again after publishing. The scan will not replace judgment, but it gives you a repeatable way to check speed, findability, accessibility, trust, action and copy credibility.

Useful next steps inside Clunky AI:

• speed checks
• run a free Clunky AI scan
• compare AI builder pages

Related deep dives:

• Website health check: what to actually test in 2026 (and what to skip)
• Bolt.new SEO: fixing the basics AI didn't ship

References

• Google: image SEO best practices