Core Web Vitals optimization is the process of diagnosing and fixing page experience issues that directly impact your search rankings and user satisfaction. Google uses three specific metrics—Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS)—as ranking signals, making this workflow essential for competitive SEO.
This workflow takes you through a systematic approach to identify problematic pages, understand what's causing poor Core Web Vitals scores, and implement specific fixes. By the end, you'll have actionable data showing which pages need attention and a clear roadmap for technical improvements.
What You'll Need
Access to Google Search Console for your website, plus the ability to run tests on PageSpeed Insights and GTmetrix. You'll also need development access to make changes to your site's code, images, or hosting configuration. Having a staging environment is recommended for testing fixes before deployment.
Step 1: Identify Problem Pages in Search Console
Time: 15 minutes | Tool: Google Search Console Navigate to the "Page experience" section in Google Search Console, then click on "Core Web Vitals." This report shows real user data (field data) from the Chrome User Experience Report. Look at both Mobile and Desktop tabs to see which URLs are marked as "Poor" or "Needs Improvement." Export the list of poor-performing URLs by clicking the export icon in the top right. Focus first on pages with the highest impressions that are failing Core Web Vitals—these give you the biggest SEO impact. The report groups URLs by similar issues, so you can often fix multiple pages with the same solution. Note which specific metrics are failing for each URL group.
Step 2: Run Detailed Performance Analysis
Time: 30 minutes | Tool: PageSpeed Insights Take the top 5-10 failing URLs from Search Console and run each through PageSpeed Insights. For each URL, analyze both the Field Data (real user metrics) and Lab Data (simulated test environment). The Field Data confirms Search Console findings, while Lab Data helps you understand specific technical causes. In the Diagnostics section, look for opportunities like "Eliminate render-blocking resources," "Properly size images," or "Reduce unused CSS." Screenshot or document the specific recommendations for each page—you'll use these as your fix checklist. Pay special attention to LCP elements identified in the "Largest Contentful Paint element" section.
Step 3: Deep Dive with GTmetrix Analysis
Time: 45 minutes | Tool: GTmetrix Run your worst-performing pages through GTmetrix using the "London, UK" test location and Chrome browser to get more granular data. GTmetrix provides waterfall charts that show exactly when each resource loads, helping you identify bottlenecks that PageSpeed Insights might miss. In the Structure tab, review the Web Vitals section for specific CLS and LCP issues. The Waterfall tab shows loading sequence problems—look for large images loading early, render-blocking CSS/JS, or third-party scripts causing delays. Document any resources taking longer than 2 seconds to load or files larger than 500KB that could be optimized.
Step 4: Categorize and Prioritize Fixes
Time: 20 minutes | Tool: Google Search Console Create a spreadsheet organizing your findings into fix categories: Image optimization (oversized hero images affecting LCP), Code optimization (render-blocking CSS/JS), Layout stability (missing dimensions causing CLS), and Server response (slow TTFB affecting all metrics). Group URLs facing similar issues together. Prioritize fixes by impact: Start with image compression and proper sizing for LCP issues, then tackle render-blocking resources. CLS fixes often involve adding explicit width/height attributes to images and ads. Use the Search Console data to focus on pages with highest search traffic first—fixing one template often resolves issues across multiple pages.
Step 5: Implement and Monitor Changes
Time: 60-90 minutes | Tool: PageSpeed Insights Begin implementing fixes starting with the highest-impact items. Common quick wins include compressing images to under 200KB, adding width/height attributes to images, preloading critical resources, and deferring non-essential JavaScript. For each change, re-test individual pages in PageSpeed Insights to confirm improvements. After deploying fixes, monitor the "Core Web Vitals" report in Search Console weekly. Field data updates can take 28 days to fully reflect changes, so be patient. Set calendar reminders to check progress monthly, as new content or code changes can introduce new Core Web Vitals issues.
Common Pitfalls
- Testing only Lab data instead of monitoring Field data from real users in Search Console
- Focusing on Desktop performance when mobile users are your primary traffic source
- Implementing fixes without testing on staging first, potentially breaking site functionality
- Ignoring CLS issues caused by ads or third-party widgets that load asynchronously
Expected Results
Within 28 days, you should see improved Core Web Vitals scores in Search Console for pages where you've implemented fixes. Good scores are LCP under 2.5 seconds, FID under 100 milliseconds, and CLS under 0.1. Track organic traffic changes to optimized pages—improved page experience often correlates with better rankings and user engagement metrics.