Do 3D websites slow a site down or hurt SEO? What matters, and what doesn’t

What Google measures, and how much it counts

web.dev, Google’s site for web developers, defines three Core Web Vitals. Largest Contentful Paint (LCP) is how long the main content takes to appear: good is 2.5 seconds or less, poor is over 4. Interaction to Next Paint (INP) is how quickly the page responds to a click, a tap or a key: good is 200 milliseconds or less, poor is over 500. Cumulative Layout Shift (CLS) is how much things jump about while the page loads: good is 0.1 or less, poor over 0.25.

They’re judged on real visits, at the 75th percentile, for phones and computers separately: a page passes when at least three in four visits are good on all three. The visits come from the Chrome UX Report, which only covers pages and sites with enough visitors to be statistically meaningful. A new small site may have no data at all, and Search Console’s Core Web Vitals report will simply say there isn’t enough.

And how much do they weigh? Google’s own page on page experience says Core Web Vitals are used by its ranking systems, but that good results don’t guarantee a top ranking, and that Google always tries to show the most relevant content, even when its page experience is poor. Speed breaks ties between helpful pages; it doesn’t replace being the helpful page.

Where a 3D page can lose

Weight. Everything a scene needs must download before it can be drawn — library, code, models, textures, photos. For scale, the HTTP Archive’s 2025 Web Almanac put the median home page at 2.6 MB on phones and 2.9 MB on computers in July 2025, and in its field data, 57% of mobile home pages under 1 MB passed all three Core Web Vitals, against 30% of those of 5 MB or more.

Work on the main thread. INP suffers when long tasks keep the browser busy — web.dev calls any task over 50 milliseconds a long one — and loading, parsing and running a large script is the kind of work it names. A 3D library is a large script.

Words inside the scene. Google’s guide for developers is explicit: content rendered in a canvas isn’t indexed. Its guide to JavaScript problems gives WebGL as an example of something Googlebot doesn’t support. A heading that exists only inside the 3D is, for search, not there. Nor does Google scroll or click on a page, so words that only arrive after an interaction may never be seen.

Phones. Google indexes and ranks the mobile version of a page, and phones are where a scene’s weight shows: the three.js manual notes that a phone’s screen can have three pixels for each one of layout, which means nine times the pixels to draw.

What the kits do about it

Text first, for search. Search engines and screen readers get the kits’ words from the HTML: headings, paragraphs, prices, buttons, sitting on top of the scene instead of inside it. Product’s statement, which is also drawn in 3D, is repeated in the HTML, and each Forest photo has a written description. The zip also carries the title, the description, the sharing tags, robots.txt, the page’s language and, with your domain, a sitemap and a canonical address.

A known weight. This site’s build of 27 September 2026 measures three.js — the one library behind all four kits — at 142 KB compressed, with each scene’s own code in a separate file that loads after the page’s first script. Between 19 and 27 files, 1.1 to 3.7 MB before the typefaces, make up a kit’s download, and the bulk of it is the demo’s imagery or model, which yours replace. The wizard shrinks oversized photos and pictures before they go in, and turns away models over 25 MB.

Fewer pixels than the screen could take. However dense the display, no kit renders more than 1.75 times the layout’s resolution; on phones Forest stops at 1.5 and steps down by quarters if its frames run slow. A hidden tab draws nothing at all.

Lighter second visits. Scripts and typefaces are sent with headers asking browsers to keep them for a year, and Cloudflare Pages delivers the files from its network. Without WebGL, the text and buttons stay usable, and Forest falls back to your photos, flat.

Checking your own site

Field data first: once your site has enough visitors, Search Console’s Core Web Vitals report groups its pages by status, for phones and computers, from the same Chrome UX Report. Until then it says there’s no data, which on a new site is normal, not a failure.

Whatever the report says, the biggest wins on a 3D page are usually the plainest: lighter pictures and models, every important word in the HTML, and a scene that isn’t drawing more pixels than the screen needs.

Questions

Is a 3D website bad for SEO?

Not in itself. It hurts when the words live only in the scene, which Google doesn’t read, or when the page is so heavy that visits turn out poor on the Core Web Vitals. With its words in HTML and its weight under control, a 3D page is judged like any other — on relevance first, as Google says.

Can Google see what’s in a 3D scene?

No. In Google’s words, content rendered in a canvas — where WebGL draws — isn’t indexed, and Googlebot doesn’t support WebGL. It reads the HTML around the scene: headings, text, image descriptions, links.

What are good Core Web Vitals?

According to web.dev: Largest Contentful Paint within 2.5 seconds, Interaction to Next Paint of 200 milliseconds or less, and Cumulative Layout Shift of 0.1 or less, each for at least 75% of real visits, on phones and on computers separately.

Why does Search Console show no Core Web Vitals for my site?

Because the data comes from real Chrome visits, and the Chrome UX Report only includes pages and sites with enough of them to be statistically meaningful; Google doesn’t publish the threshold. A new or small site often has none, and there’s nothing to fix about that.

Do Promti’s kits pass the Core Web Vitals?

We don’t publish a score, because the Core Web Vitals are measured on real visits to each site, on its visitors’ devices, with its own photos and model. What a kit controls is what’s listed above: the words in HTML, the weight counted, the drawing capped, the files cached. The live demos are there to try on your own phone.