Custom-Built Website? How to Check If It Is Actually Fast

If you built your website with custom code, or paid a developer to, you have probably heard that custom is faster than a template site from Wix or Squarespace. Sometimes it is. But custom code is not automatically fast, and one setting most people never see decides which way it goes. The good news: you can check it in about thirty seconds, no developer required.

Full disclosure: the data in this guide comes from Stackra's own research across 1.1 million US business websites, and we build a website audit, so weigh the closing suggestion with that in mind. The check itself uses your own browser and Google's free tools, not ours.

The setting that decides your speed: how your page renders

Every website gets its content onto the screen in one of two broad ways. Knowing which one yours uses tells you most of what you need.

• •Ships finished HTML: the page arrives with your headings, text, and images already in it. The visitor's phone just displays it. This is fast.
• •Ships a blank shell: the page arrives nearly empty, then runs code to build itself inside the visitor's browser. The phone does the work. This is slower, especially on older or cheaper phones.

Why it matters for speed and for AI search

When the phone has to assemble the page, slower devices fall behind, and that shows up in Google's Core Web Vitals, the speed scores that feed search ranking. There is a second cost too. Many AI crawlers, including the ones behind ChatGPT and Google's AI Overviews, read the raw HTML and do not run that build step. If your page ships a blank shell, they see almost nothing.

The 30-second check: view your page source

You do not need any tools for this. Open your homepage in a browser and view the page source. On Windows press Ctrl+U. On a Mac press Cmd+Option+U. A window opens showing the raw code your site sends before any building happens. Search that window with Ctrl+F or Cmd+F for your main headline text.

• •You find your headline and paragraphs: your site ships HTML. You are in good shape. Move on to content and links.
• •You see only a short block with a blank container like a lone div and some script tags: your site builds in the browser. This is the pattern that scores lowest on speed and is hardest for AI to read.

Confirm it with a free speed test

To put a number on it, run your homepage through Google PageSpeed Insights. It reports your Core Web Vitals using real-world data and flags what is slowing the page down.

What the data actually shows

Across 1.1 million sites the pattern is clear and a little surprising. No-code builders like Wix and Squarespace pass Core Web Vitals more often than hand-built sites do, because they handle rendering for you. But custom code is not doomed. Hand-built sites that ship finished HTML are the fastest sites of all.

If your site builds in the browser, here is the fix

This is a conversation with whoever builds your site, not an emergency and usually not a full rebuild. Ask them about one of these, roughly in order of effort:

• •Add a pre-render or static export step, so each page is saved as finished HTML at build time. Often the smallest change.
• •Turn on server-side rendering if your framework supports it, so the server sends complete HTML. Next.js, Nuxt, and Remix all do this.
• •If you are on a modern host like Vercel or Netlify, ask whether their built-in pre-render or edge options cover your pages.

Already on a no-code builder?

Then this is mostly handled for you. Wix, Squarespace, Shopify, and similar platforms ship HTML by default and pass Core Web Vitals at a high rate. Your speed is rarely the bottleneck. Spend your effort on the content and links that actually move visibility.

The one thing to remember

Speed is not decided by whether you used custom code or a builder. It is decided by whether your pages arrive as finished HTML or build themselves in the browser. Check yours in thirty seconds with view-source, and if it comes up empty, you now know the exact question to ask.