How to Optimize WordPress Core Web Vitals — Real Client Example (2025)

If your WordPress site feels sluggish, fails Core Web Vitals in Search Console, or loads in more than a few seconds on mobile, you're not alone. Many site owners only notice speed problems after adding page builders, plugins, tracking scripts, and large images. This article shows you, step by step, how we optimized WordPress Core Web Vitals for a real client — and how you can apply the same process to your own site.

1. Quick checks to confirm your WordPress Core Web Vitals are failing

Before changing plugins, themes, or hosting, you need to confirm there's really a performance problem. These quick checks take less than 10 minutes and give you an honest baseline.

• Open your site on 4G: Use your phone on a mobile network. If your homepage or key landing pages feel slow, your visitors feel it too.
• Run a PageSpeed Insights test: Test your homepage, a high-traffic blog post, and any critical landing pages. Pay close attention to the mobile scores and the Core Web Vitals section.
• Check Search Console Core Web Vitals: Look for URLs flagged as "Poor" or "Needs improvement" for LCP, CLS, or INP.
• Check for obvious bloat: Heavy sliders, pop-ups, chat widgets, analytics tags, and marketing plugins are often the first suspects when WordPress performance optimization becomes necessary.
• Ask your team: If your marketing or content team says "the site feels slow or jumpy", treat that as a signal to start the checklist.

2. Common reasons WordPress sites fail Core Web Vitals

Once you know your site is struggling, the next step is understanding why. After hundreds of WordPress audits, we see the same root causes of poor Core Web Vitals over and over again.

3. Pre-optimization audit checklist

Before you start making changes, capture a snapshot of how your WordPress site performs today. That way you can see exactly what your work changed later.

4. Real Before & After client example

One FASTRANK client, a content-heavy WordPress site with a WooCommerce store, came to us with poor mobile Core Web Vitals. Their site relied on a multi-purpose theme, Elementor layouts, many marketing plugins, and unoptimized hero images that hadn't been cleaned up in years.

After going through a structured WordPress Core Web Vitals checklist — removing slow plugins, compressing images, fixing render-blocking files, and stabilizing layout shifts — their mobile PageSpeed score jumped from 31 to 89, LCP dropped from 6.8s to 1.9s, CLS went from 0.32 to 0.01, and organic conversions increased by 17%.

5. Full checklist to fix WordPress Core Web Vitals

Here's the exact checklist we use internally when we deliver a WordPress speed optimization service. You can go through it yourself or use it as a framework when working with a developer.

3.1 Removing or Replacing Performance-Killing WordPress Plugins

Plugins are the number one reason why otherwise healthy WordPress sites fail Core Web Vitals. Each installed plugin injects JavaScript, CSS, database queries, and external requests — often on every page. This additional work increases main-thread time, delays rendering, and negatively impacts LCP, INP, and CLS.

This step focuses on structured plugin cleanup to restore performance safely.

The Plugin Cleanup Checklist

1) Surgical Plugin Deactivation & Removal

Action: Deactivate and remove any plugin not actively used in the last 30 days. Unused plugins still add code, database overhead, and potential security issues.

Tip: If a plugin is only needed for a specific page (for example, a form or landing-page builder), use a tool like Perfmatters, Asset CleanUp, or LiteSpeed's CSS/JS controls to load scripts on that page only — not site-wide.

2) Code Scavenging (Critical Step)

Deleting a plugin does not always remove its leftover code or data. Many plugins leave behind CSS/JS files, database tables, and autoloaded options that keep slowing your site.

Action: Manually audit your wp-content/plugins directory, theme files, and database for orphaned code and tables.

Expert Insight: Use Chrome DevTools → Coverage Tab or a waterfall report to identify unused JS/CSS linked to old plugins.
Related deep-dive:
WordPress Speed Optimization Guide (2025)

3) Plugin Consolidation

Action: Replace multiple single-purpose plugins (popups, social sharing, minor visual effects) with one lightweight, well-maintained alternative. This reduces HTTP requests and improves speed immediately.

Looking for a platform-specific example instead? Check our Shopify case study:
Before/After Shopify Speed Optimization — Case Study

4) Prefer Native WordPress & Theme Features

Action: Whenever possible, use native block editor features (FAQ blocks, columns, buttons, galleries) and built-in theme options instead of heavy third-party addons.

More best practices inside:
WordPress Speed Optimization Services — What You Should Expect

Step 2: Fix image bloat and LCP

Image optimization is one of the fastest ways to see Core Web Vitals improvement:

• Keep hero and featured images under ~200KB where possible.
• Convert images to modern formats like WebP using a plugin or CDN.
• Enable lazy loading for below-the-fold images and embeds.
• Set width/height attributes to avoid unexpected layout shifts.
• Serve properly sized images instead of oversized originals.

Step 3: Reduce render-blocking CSS and JS

Once images and plugins are under control, move to critical resources:

• Generate and inline critical CSS for above-the-fold content.
• Load non-critical styles asynchronously or split them by template.
• Add defer or async to non-essential JavaScript.
• Delay third-party scripts (chat, tracking, A/B testing) until user interaction when possible.

Step 4: Stabilize Core Web Vitals (LCP, CLS, INP)

A proper WordPress Core Web Vitals fix focuses on LCP, CLS, and INP together:

• LCP: Prioritize the main hero image or heading, minimize competing requests, and reduce server response time.
• CLS: Reserve space for images, ads, banners, and embeds so they don't push content down as they load.
• INP: Limit heavy JavaScript execution, reduce main-thread blocking, and avoid unnecessary animations and sliders.

Step 5: Upgrade hosting, caching, and CDN

WordPress is sensitive to slow hosting and weak caching. For stable Core Web Vitals:

• Use performant hosting (managed WordPress, LiteSpeed, or cloud-based providers).
• Configure full-page caching with plugins such as LiteSpeed Cache, WP Rocket, or W3 Total Cache.
• Enable Brotli or GZIP compression for text resources.
• Use a CDN like Cloudflare to cache static assets globally and reduce latency.

Step 6: Re-test and document improvements

After working through the checklist, repeat the same tests you ran at the beginning. Capture new PageSpeed Insights screenshots, GTmetrix waterfalls, and updated Core Web Vitals reports from Search Console. This creates a clear before/after story to share with your team or with clients.

6. Business impact of fixing Core Web Vitals

The goal of this checklist isn't just a nicer score in a lab tool. When you systematically improve your WordPress Core Web Vitals, you usually see:

• Higher conversion rate: Visitors stop abandoning pages before key content loads.
• Lower bounce rate: Users stay longer, consume more content, and browse more pages.
• Better ad and campaign performance: Faster landing pages improve Quality Score, which can reduce CPC on Google and Meta.
• Stronger SEO: Stable Core Web Vitals support your long-term organic rankings and crawl efficiency.

7. DIY fixes vs hiring a WordPress speed expert

Many checklist items — plugin cleanup, basic image compression, and simple caching — are safe to handle yourself. But other tasks, especially those that touch PHP, theme files, JavaScript, or database structure, can break layouts or cause downtime if done incorrectly.

If your site is a key revenue channel, or you're running paid ads to slow pages, consider working with a specialist. A good partner offering WordPress speed optimization services will:

• Run a detailed audit and explain findings in plain language.
• Follow a safe deployment process with backups and staging.
• Focus on measurable metrics (Core Web Vitals, load time, conversions).
• Provide a transparent before/after report so you can see the ROI.

At FASTRANK, we provide a structured WordPress performance optimization process and dedicated plans for site owners who want expert help instead of spending weeks debugging plugins and scripts themselves. You can view our WordPress optimization plans if you'd rather hire a WordPress speed expert than go through every step alone.

8. Frequently asked questions

Here are some of the most common questions we hear from site owners going through this WordPress Core Web Vitals checklist for the first time.

9. How to get started with WordPress performance optimization

If this feels like a lot, remember you don't need to tackle every point in one day. Start with the easiest wins: plugins, images, and obvious layout issues. Then work your way toward deeper technical changes like critical CSS, server tuning, and script deferral.

• Use this article as your working checklist and tick off items as you go.
• Keep before/after screenshots and reports so you can see how much faster your site becomes.
• Share the checklist with your developer or agency so everyone is aligned on priorities.

And if you'd rather have an expert handle everything, our team at FASTRANK offers a structured WordPress site speed optimization service with clear pricing, guaranteed improvements, and a detailed before/after report. If you also run a Shopify store, you can pair this article with our Shopify speed optimization checklist to keep both platforms fast.