Core Web Vitals consulting for Next.js and React sites
Search Console says your Core Web Vitals assessment failed. PageSpeed Insights shows red numbers. You want to know why, and you want it fixed without breaking the site.
I'm a Next.js developer with an SEO background. I find the cause in real user data, then fix it in your code.
I reply within one business day. No obligation.
What Google measures
Core Web Vitals are three numbers from real visitors on Chrome. Google checks the 75th percentile, so most of your visitors have to get a good experience, not just you on fast Wi-Fi (web.dev).
LCPLargest Contentful Paint
- What it measures
- How fast the main content appears
- Good
- 2.5 seconds or less
INPInteraction to Next Paint
- What it measures
- How fast the page responds to clicks and taps
- Good
- 200 milliseconds or less
CLSCumulative Layout Shift
- What it measures
- How much the page jumps around while loading
- Good
- 0.1 or less
INP replaced First Input Delay in March 2024. Many sites that passed before now fail on INP, especially JavaScript-heavy ones.
What usually slows a Next.js site
When LCP fails
- The hero image loads late
It isn't marked as a priority, or it's served far larger than it's shown.
- The page waits on data
Server rendering blocks on a slow API or database call, with nothing cached.
- Fonts block the text
Web fonts load from another domain instead of with the page.
When INP fails
- Too much JavaScript runs on the page
A
"use client"near the top of the tree turns a whole page into client code. - Third-party scripts compete for the main thread
Chat widgets, A/B testing tools and tag managers all run when a visitor clicks.
- Heavy work happens on every click
Filtering a long list or re-rendering a large component tree blocks the response.
When CLS fails
- Images and embeds have no reserved space
The text jumps when they load.
- Banners appear late
Cookie notices and promo bars push the page down.
- Fonts swap and change size
The layout shifts when the real font arrives.
Each of these has a known fix in Next.js. The hard part is finding which ones apply to your pages.
How I work on it
- Real user data first
I start with field data from the Chrome UX Report and Search Console, not a single lab test. That tells me which pages and which metric actually fail.
- Find the cause per template
I profile the failing templates and trace each problem to a component, script or request.
- Fix the biggest wins first
Usually a handful of changes cover most of the gap.
- Check the field data again
Google uses a 28-day window, so real results show up over the following weeks.
If the slowness comes from the server or hosting setup, I can fix that side too.
Deployment and hostingWhat I won't promise
A Lighthouse score of 100.
It's a lab test on one device. Real user data is what Google uses, and what your visitors feel.
A ranking jump.
Google says good Core Web Vitals don't guarantee your pages will rank at the top. It still shows the most relevant content first, even when page experience is weaker (Google).
What you do get is a faster site, which helps visitors whether or not it moves rankings.
Pricing
- Option
- Core Web Vitals review
- Price
- $249
- What it covers
- Which pages and metrics fail, the cause of each, and a ranked fix list
- Option
- Fixes
- Price
- From $400, or $25/hour
- What it covers
- Making the changes in your code and checking the results
The review price is credited toward the fixes if you go ahead within 30 days.
If you're not sure speed is the main problem, start with the technical SEO audit. It covers Core Web Vitals along with rendering, indexing and metadata. Both are part of my JavaScript SEO work.
Questions about Core Web Vitals
At least one of the three metrics, LCP, INP or CLS, is outside the good range for 75% of real visitors on that page group. Search Console shows which metric and which URLs. The cause is usually one of a few repeat problems: late images, too much JavaScript, or content that shifts while loading.
Find which metric fails first, then fix the cause on the affected templates. After the fix, Google needs up to 28 days of new data before the assessment updates. Use Search Console's validation to track it.
Yes, as one part of page experience. Google says good scores align with what its ranking systems reward, but relevant content comes first. Speed helps most when several pages are equally helpful for a search.
It gives you good tools, like server rendering, image optimization and font loading. It doesn't stop you from shipping too much client JavaScript or heavy third-party scripts. Most slow Next.js sites are slow because of how they were built, not because of Next.js.
Field data comes from real Chrome users over the last 28 days. Lab data, like a Lighthouse test, is one simulated visit. Google uses field data for Core Web Vitals. Lab tests are useful for finding causes, not for proving results.
Tell me about your site
Send me your URL and which metric is failing, if you know. I'll tell you where I'd start.
Tell me about your siteI reply within one business day. No obligation.
Get in Touch
Other ways to reach me
I'm available via email and messaging platforms.
Chat with me
Quick questions or follow-ups
Munim Rahman
Fullstack Developer • Next.js & Nest.js
Dhaka, Bangladesh