Three numbers describe how a page feels to a visitor: how fast the main content appears, how quickly it responds, and whether it jumps around. Here is what each one means and where the usual fixes are.
When a business owner says their website is slow, they usually mean one of three different things. The page takes a long time to show anything useful. It looks ready but does not respond when tapped. Or the text moves just as they go to press a button. Google measures each of these separately, and together they are called Core Web Vitals.
The first is Largest Contentful Paint, or LCP. It measures how long it takes for the biggest visible element, usually a hero image or a large heading, to appear on screen. Google considers 2.5 seconds or less to be good and anything over 4 seconds to be poor. On most business sites we audit, the culprit is an image. A hero photo straight off a phone camera can be four or five megabytes. Resizing it to the width it is actually displayed at, saving it as WebP or a well-compressed JPEG, and not lazy-loading it, since it is the first thing people see, can cut seconds off this number on its own.
The second is Interaction to Next Paint, or INP. It replaced an older measure called First Input Delay in March 2024, and it looks at how quickly the page responds to taps, clicks and key presses throughout the visit, not just the first one. A good score is 200 milliseconds or less. Slow INP almost always means too much JavaScript competing for the phone's processor. Chat widgets, tracking scripts, sliders and page builders are the usual contributors. Removing a script that nobody uses will improve it more than any clever optimisation.
The third is Cumulative Layout Shift, or CLS. It scores how much the page moves around while loading. Anything at or below 0.1 is good. You have felt a bad one: you start reading, an advert or image loads above the text, and everything drops down. The fix is usually simple. Give every image and embed a fixed width and height, so the browser reserves space before the file arrives, and avoid inserting banners above content that is already on screen.
One point that trips people up is the difference between lab data and field data. Tools like Lighthouse run a test on a simulated device and give you a score straight away. That is useful for finding problems and checking fixes. But Google's ranking signal comes from field data, meaning real visitors on real phones and real connections, gathered over roughly the previous 28 days and judged at the 75th percentile. A site can score well in the lab and still fail in the field because your customers are on mid-range Android phones and patchy mobile data, which is the case for a large share of Indian users.
To see your real numbers, open PageSpeed Insights and enter your address. If the site has enough traffic, the top section shows field data. Google Search Console also has a Core Web Vitals report that groups your pages into good, needs improvement and poor, so you can see whether a problem is one template or the whole site.
Our order of work is nearly always the same. Fix the hero image first. Set dimensions on all images. Remove scripts that nobody can justify. Check that fonts are not blocking the first paint. Then test on a real mid-range phone over a mobile connection, not on a fast laptop. Most sites improve meaningfully after those five steps, without any redesign.
It is worth saying what speed will not do. A fast site will not rescue weak content or a confusing offer. Core Web Vitals are one ranking signal among many and generally act as a tie-breaker between pages of similar quality. Where speed matters most is with people: visitors leave slow pages, and every visitor who leaves before the page loads is an enquiry you paid to attract and then lost.