The Complete Guide to Improving Core Web Vitals on Custom

Custom wholesale sites often struggle with Core Web Vitals because functionality comes first, performance second. Product catalogs with thousands of SKUs, complex pricing, and bulk ordering features create challenges that standard advice does not address.

Here is how to fix Core Web Vitals on your wholesale platform.

Understanding the Three Metrics for Custom Sites

Google measures three specific aspects of user experience:

Largest Contentful Paint (LCP) tracks how quickly your main content appears. Target is under 2.5 seconds.

Interaction to Next Paint (INP) measures responsiveness when users click, tap, or type. Target is under 200 milliseconds.

Cumulative Layout Shift (CLS) tracks visual stability when elements move around during loading. Target is under 0.1.

Step 1: Measure Your Current Performance

Start in Google Search Console under the Core Web Vitals report. The report groups URLs by status: good, needs improvement, or poor.

Focus on fixing pages in the "poor" category first.

Run PageSpeed Insights on your homepage, main category pages, and a typical product page. Pay attention to the field data section showing real user experiences.

A technical SEO audit identifies exactly which elements cause problems on your specific site.

Step 2: Fix LCP on Catalog Pages

Wholesale catalogs are LCP nightmares. Here is how to speed them up:

Optimize hero images. Convert to WebP format, which reduces file sizes by 25 to 35 percent compared to JPEG. Set explicit width and height attributes.

Implement lazy loading correctly. Lazy load images below the fold, but never lazy load your LCP element. The first visible image needs to load immediately.

Preload critical resources. Add preload hints for your main CSS file and fonts used in above-the-fold content.

Use a CDN. Content delivery networks serve images from servers closer to your buyers. For wholesalers serving customers across regions, a CDN cuts LCP times significantly.

Step 3: Improve INP for Complex Interactions

Wholesale sites have heavy JavaScript for pricing calculators, inventory checks, and cart updates. These features often make your site feel sluggish.

Defer non-critical JavaScript. Your pricing calculator does not need to load before the user scrolls to it. Use defer or async attributes on scripts not needed immediately.

Break up long tasks. If JavaScript runs for more than 50 milliseconds without a break, it blocks user interactions. Split complex calculations into smaller chunks.

Optimize event handlers. Every click and input triggers code. Audit your event listeners and remove any running expensive operations unnecessarily.

Step 4: Eliminate CLS Problems

Layout shifts frustrate users and hurt scores. Common culprits on wholesale sites include:

Product images without dimensions. Every image tag needs width and height attributes. Without reserved space, images push content around when they load.

Dynamic pricing displays. When prices update based on quantity or customer tier, reserve the space in advance. Use min-height CSS properties on price containers.

Late-loading fonts. Web fonts that load after the initial render cause text to reflow. Use font-display: swap and preload your primary fonts.

According to RUMvision research, Vodafone saw an 8 percent increase in sales after improving their LCP by 31 percent.

Step 5: Optimize Your Backend

Frontend fixes only go so far if your server responds slowly.

Enable server-side caching. Cache product data, pricing tiers, and category information. Regenerate caches on a schedule rather than on every page load.

Optimize database queries. Complex wholesale catalogs often have slow queries joining multiple tables. Index your most-used query patterns.

Use HTTP/2 or HTTP/3. Modern protocols allow multiple requests over a single connection, speeding up page loads for content-heavy pages.

Working with SEO performance specialists helps identify backend bottlenecks not visible from standard testing tools.

Step 6: Set Up Ongoing Monitoring

Core Web Vitals are not a fix-once situation. New features and content updates can reintroduce problems.

Use real user monitoring. Tools like Google's web-vitals library capture actual user experiences and alert you to regressions.

Set performance budgets. Define maximum file sizes and script execution times. Block deployments that exceed these budgets.

Review monthly. Check your Search Console Core Web Vitals report regularly. Address new issues before they accumulate.

A data-driven SEO approach connects performance metrics to business outcomes like conversion rates.

Prioritizing Your Fixes

You can not fix everything at once. Prioritize based on:

1. Pages with the most traffic and worst scores

2. Fixes that address multiple issues at once

3. Changes that improve user experience beyond SEO

Focus on getting pages from "poor" to "needs improvement" before optimizing further. The biggest ranking impact comes from fixing the worst pages first.

Expected Timeline To get Results for Wholesellers

Google uses a 28-day rolling average for Core Web Vitals data. After making improvements, expect about a month before seeing full impact in Search Console reports.

Performance improvements often have a larger impact on conversion rates than on rankings. Track both metrics to understand the full value of your optimization work.

Your wholesale platform has unique challenges, but Core Web Vitals improvements follow consistent patterns. Start with measurement, focus on high-impact fixes, and establish monitoring to maintain gains over time.