Every website vendor says their sites are fast. You don't have to take anyone's word for it, including ours. Google gives you free tools to test any page, and the numbers they report are the same ones Google uses to describe page experience. Here's what they mean, in plain words, and how to use them when you're judging a dealer website.
Two kinds of numbers: lab and field
There are two ways to measure speed, and it's worth knowing which one you're looking at.
- Lab data: a test that loads the page once, on a simulated phone or desktop, and scores it. Lighthouse does this. It's repeatable and good for comparing pages, but it's one test, not your real visitors.
- Field data: measurements from real Chrome users who visited the site over the last 28 days, collected in Google's Chrome UX Report. This is what Google's Core Web Vitals assessment is based on. Smaller sites, or new ones, may not have enough visitors to show field data yet.
PageSpeed Insights (pagespeed.web.dev) shows both when it can: field data at the top, if Google has it, and a Lighthouse lab test below.
The three Core Web Vitals
Core Web Vitals are three measurements Google uses to describe how a page feels to use. Google calls each one "good" when at least 75% of page visits meet the threshold:
- Largest Contentful Paint (LCP): how long until the main thing on the page, usually the hero photo or headline, shows up. Good is 2.5 seconds or less.
- Interaction to Next Paint (INP): how quickly the page responds when someone taps or clicks. Good is 200 milliseconds or less. INP replaced an older measure, First Input Delay, in March 2024.
- Cumulative Layout Shift (CLS): how much things jump around while the page loads, like a button moving just as you tap it. Good is 0.1 or less.
On a car page, these map to things shoppers feel: how fast the first photo appears, whether the gallery responds when they swipe, and whether the price box stays put.
The four Lighthouse scores
A Lighthouse report gives four scores from 0 to 100. Performance is the speed score, built from lab measurements like LCP, layout shift and how long the page is blocked by scripts. Accessibility checks things like color contrast, labels and alt text, which matter for shoppers using screen readers and for everyone on a small screen in the sun. Best Practices checks security and modern code habits. SEO checks the basics search engines need: titles, descriptions, crawlable links, valid structured data and so on.
Why mobile scores move around
Lighthouse's mobile test simulates a mid-range phone on a slow connection, so small differences in network timing change the result. Run it three times and you'll often get three different performance scores. That's normal. A fair way to report it is a range, or the middle of several runs.
Here's an honest example. We ran Lighthouse 12.8 on the home page of a live dealer site running our template on October 15, 2026. On desktop, three runs scored the same every time: Performance 100, Accessibility 100, Best Practices 96 and SEO 100, with LCP 0.5 seconds and CLS 0. Those were lab scores only; we didn't have Google's field data for that test, so we don't claim a Core Web Vitals pass from them.
What makes dealer websites slow
In our experience, the usual causes are the same from site to site:
- Big photos. Car pages are photo-heavy. Sending a full-size picture to a phone wastes seconds. Modern sites resize each photo for the screen and send it in a smaller format like AVIF or WebP.
- Too many widgets. Chat tools, ad tags, trade-in tools and pop-ups each add scripts. Load them after the page is ready, and remove the ones nobody uses.
- Pages built on every visit. If the server assembles each car page from scratch for every shopper, it's slower than serving a page that was built ahead of time and cached close to the visitor.
- Old code. Platforms that have been patched for years carry a lot of code that every page has to download.
Why speed matters for a car lot
A shopper comparing three dealers on a phone will usually give each site a few seconds. If your first photo and price show up quickly, you're in the comparison. If the screen sits blank, or the page jumps as they try to tap "Check availability", they go back to the search results and pick someone else. You won't see those shoppers in your CRM, because they never got far enough to fill in a form. That's why it's worth checking speed on the pages shoppers actually land on: car pages and model pages, not just the home page. It's also why accessibility matters: clear contrast, readable text and labeled buttons help every shopper on a small screen, not only those using assistive technology.
How our template is built
Our dealer website template runs on Next.js 16 and React 19 and is hosted on Vercel. Car pages and landing pages are built ahead of time and cached, inventory reloads from the feed every 15 minutes, photos are resized and served as AVIF or WebP, and third-party tools load after the page is interactive. You can try the same pages on our demo sites: Classic, Luxury and Clean.
How to test your own site in five minutes
- Go to pagespeed.web.dev and enter your home page.
- Note whether it shows real-user field data and whether it passes Core Web Vitals.
- Look at the four Lighthouse scores for mobile, then switch to desktop.
- Run it again two more times and write down the range.
- Repeat with one of your car pages, since that's where shoppers decide.
Speed isn't everything. A fast page still needs good photos, a clear price and an easy next step. But it's the part you can measure for free today. If you'd like us to walk through your results with you, book a demo.