How to Fix Core Web Vitals Issues: A Step-by-Step Guide for 2025

Core Web Vitals are not optional anymore. Google baked them into its Page Experience ranking signal in 2021, and in 2025, failing these metrics is actively costing Canadian businesses rankings they worked years to earn. If your site is bleeding traffic and you cannot figure out why, your LCP, INP, or CLS scores are the first place to look — and fixing them is exactly what our technical SEO work at The SEO Pros is built around. This guide gives you the exact process we use for clients across the country.

how to fix Core Web Vitals issues shown on Google Search Console performance report dashboard

Step 1: Diagnose Before You Touch Anything

What You Need

Before you change a single line of code, you need accurate data. Open Google Search Console and navigate to the Core Web Vitals report under the Experience section. This report pulls from real user data — what Google calls field data — and it segments your URLs into Good, Needs Improvement, and Poor categories. That segmentation matters. Do not optimize based on PageSpeed Insights alone. PageSpeed gives you lab data from a simulated environment. Google ranks you on field data from actual visitors.

Run your URLs through both PageSpeed Insights and the Chrome UX Report (CrUX). Cross-reference them. If your field data shows Poor LCP but your lab score looks acceptable, the problem is almost always render-blocking resources, slow server response time, or unoptimized images loading above the fold. We have seen this exact pattern across dozens of Toronto e-commerce sites and Calgary law firm websites. The lab score looked fine. The real users were suffering.

Use Ahrefs Site Audit or Semrush’s Site Health tool alongside Search Console. These platforms flag Core Web Vitals failures at scale, which is especially useful when your site has hundreds of pages. For our Toronto SEO clients with large service-area websites, crawling the full site first saves weeks of guesswork.

Step 2: Fix Largest Contentful Paint (LCP) First

LCP is the metric that kills the most Canadian small business websites. It measures how long it takes for the largest visible element — usually a hero image or an H1 heading block — to render. Good LCP is under 2.5 seconds. Poor LCP is anything over 4.0 seconds. Sites running bloated WordPress themes with oversized homepage banners fail this one constantly, and the owners rarely know it.

Fix your LCP in this order. First, compress and convert your hero image to WebP format. A 1.2MB JPEG hero image becoming a 180KB WebP is not unusual, and that single change can drop LCP by 1.2 seconds. Second, add fetchpriority="high" to your LCP image element so the browser prioritizes loading it. Third, eliminate render-blocking JavaScript and CSS by deferring non-critical scripts and inlining critical CSS. Fourth, switch to a faster hosting environment. Shared hosting on a Canadian server cluster is not the same as a managed WordPress host with edge caching. That difference shows up directly in your field data.

A Vancouver-based roofing contractor we worked with had an LCP of 6.8 seconds on mobile. The culprit was a 2.4MB slider image loading without lazy loading or compression, combined with three render-blocking Google Font calls. After compression, WebP conversion, font preloading, and a CDN implementation, their LCP dropped to 2.1 seconds. Within 11 weeks, their organic impressions increased 63% and they entered the local Map Pack for “roofing contractor Vancouver” for the first time.

One image fix. Eleven weeks. First Map Pack appearance. That is not a theory — that is what actually happens when you address the root cause instead of chasing the symptom.

LCP score improvement before and after optimization shown in PageSpeed Insights report

Step 3: Resolve Interaction to Next Paint (INP) Issues

INP replaced First Input Delay as the interactivity metric in March 2024. This matters because INP measures the full lifecycle of every interaction on the page, not just the first click. Good INP is under 200 milliseconds. If your score is over 500ms, users are clicking buttons and waiting. That is a conversion killer, and in competitive markets like Toronto and Ottawa, it is also a ranking killer.

The primary cause of poor INP is JavaScript running on the main thread. Long tasks — any JavaScript execution over 50ms — block the browser from responding to user input. The fix is breaking up long tasks using techniques like setTimeout chunking or the Scheduler API. We stopped recommending third-party chat widgets on service-area business pages specifically because of INP. Those widgets routinely add 300–600ms of main-thread blocking on mobile devices. No chat conversion is worth a poor Core Web Vitals score that suppresses your entire page’s ranking potential. That is a firm position, and the data backs it up.

Use Chrome DevTools’ Performance panel to identify long tasks. Filter by “Long Tasks” in the timeline. Each one is a candidate for optimization. For WordPress sites, auditing your plugin list is non-negotiable. We routinely find Edmonton and Mississauga business sites running 30+ plugins where 12 are loading scripts site-wide for functionality used on one page. Loading scripts conditionally using a plugin like Asset CleanUp cuts INP dramatically without any custom development.

Step 4: Eliminate Cumulative Layout Shift (CLS)

CLS measures visual stability. Every time an element moves unexpectedly while the page loads — an ad pushes content down, a font swap shifts a heading, an image without dimensions causes reflow — you accumulate CLS score. Good CLS is under 0.1. This metric is particularly punishing for Calgary real estate sites and restaurant websites in the GTA where above-the-fold content is dense and images load dynamically.

The fix for CLS is systematic. Set explicit width and height attributes on every image and video element so the browser reserves space before the asset loads. Use font-display: optional or font-display: swap carefully. The swap value causes layout shift if not paired with a size-adjusted fallback font. Reserve space for ads and embeds using CSS aspect-ratio containers. Never inject content above existing content dynamically unless the user explicitly triggered it.

Here is a nuanced point most developers miss: animations that use CSS top, left, margin, or width properties trigger layout recalculation and contribute to CLS. Use transform and opacity for animations instead. These run on the compositor thread and do not cause layout shift. This single change fixed a persistent CLS issue on a dental clinic website in Scarborough that had been stuck with a Poor score for months despite every other optimization being in place.

One CSS property swap. Months of frustration resolved.

Common Mistakes When Fixing Core Web Vitals

The biggest mistake we see — and it costs businesses roughly six months of ranking progress — is optimizing for desktop when 70%+ of their traffic is mobile. Google uses mobile-first indexing. Your field data in Search Console is dominated by mobile user experiences. If you fix your desktop score and ignore mobile, nothing changes in the rankings. Test on throttled mobile connections using Chrome DevTools every single time. No exceptions.

The second mistake is treating Core Web Vitals as a one-time project. Every new plugin, page template, or third-party script you add is a potential regression. We set up automated monitoring for all clients: Search Console alerts, plus monthly PageSpeed Insights checks on the top 10 revenue-driving URLs. Fixes decay. Monitoring prevents that decay from silently destroying rankings you earned.

Third: do not conflate a green PageSpeed Insights score with passing Core Web Vitals in Search Console. They measure different things from different environments. We have seen businesses celebrating a 90+ PageSpeed score while their Search Console still shows Poor field data on 60% of URLs. The field data is what Google uses. Full stop. That is what you fix for.

before and after Core Web Vitals results showing improved rankings for Canadian business website

Step 5: Validate, Monitor, and Connect Results to Rankings

After implementing fixes, request revalidation in Google Search Console under the Core Web Vitals report. Google takes 28 days to collect enough new field data to update your status. Do not expect overnight movement in rankings. The realistic timeline for seeing organic ranking improvements tied to Core Web Vitals fixes is 6 to 12 weeks, depending on how frequently Google crawls your site and how competitive your market is.

Track the right downstream metrics: CTR in Search Console, average position for your target pages, and bounce rate in GA4. Core Web Vitals improvements that stick show up in dwell time and engagement rate before they show up in ranking position. That is the leading indicator the fixes are working. We have written extensively about connecting technical wins to business outcomes on our SEO blog — the pattern holds consistently across industries and across Canadian markets.

Honest caveat: if your site is on a platform you cannot modify — certain managed e-commerce platforms or locked CMS environments — your ability to fix INP and LCP at the code level is severely limited. In those cases, the highest-leverage actions are CDN implementation, image optimization through the platform’s built-in tools, and reducing third-party scripts to the absolute minimum. Full Core Web Vitals optimization requires meaningful access to your site’s codebase and server configuration. If you do not have that access, you will hit a ceiling fast.

Across 850+ Canadian businesses we have worked with, the clients who saw the fastest and most durable results were the ones who treated Core Web Vitals as an ongoing discipline — monitoring scores monthly, auditing new plugins before installation, and maintaining a staging environment to test changes before pushing live. That discipline compounds. Over 12 months, it separates the businesses that hold their rankings from the ones that yo-yo every time Google updates its crawling thresholds.

Your Core Web Vitals scores are either helping your rankings or hurting them — there is no neutral. At The SEO Pros, we have fixed performance issues for businesses across Toronto, Calgary, Vancouver, Edmonton, and the GTA, turning Poor scores into ranking gains with measurable traffic results. If you want a technical audit that shows exactly what is failing and a clear plan to fix it, get in touch with our team today.