Tips for Improving Core Web Vitals (LCP, CLS, INP) Scores

At Mile High Themes, we take performance very seriously. All of our themes are built from the ground up to be fast and lightweight:

Clean, modern code with almost no render-blocking CSS or JavaScript
Native lazy-loading and proper image sizing
Optimized fonts and minimal external requests
Regularly updated to meet the latest Shopify Online Store 2.0 speed standards

All of our themes meet or exceed Shopify's strict requirements for performance and accessibility. But even with all of that, many stores still see lower-than-expected scores for Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), or Interaction to Next Paint (INP) in Google PageSpeed Insights or Lighthouse.

While the theme certainly plays a role in that, there are many other factors besides the theme code itself that affect these metrics. The final score is heavily influenced by:

The sections and content you add in the theme editor (huge slideshows, videos, animated banners, etc.)
Third-party apps and scripts (reviews, pop-ups, chat widgets, analytics, upsell apps, etc.)
Large or unoptimized images you upload
Custom code or apps that inject extra CSS/JavaScript
Custom fonts (especially more than 1–2 Google Fonts)

Easy Wins You Can Do Right Now (No Code Required)

Hero / Banner Images
Keep them under 500 KB and no wider than 1920 px. Use WebP format. Use a single, fast-loading static image instead of a slideshow or video on the homepage.
Reduce the Number of Sections Above the Fold
Move newsletters, trust badges, and announcement bars lower on the page if possible.
Limit Custom Fonts
Stick to one Google Font with only the weights you actually use or choose system fonts from the Shopify font picker in the typography settings.
Review Installed Apps
In Shopify admin → Settings → Apps and sales channels, look for apps that load scripts in the head or add large pop-ups. Removing or replacing even one heavy app often boosts scores dramatically. When removing apps you no longer need, check the support sites for the apps to make sure you fully uninstall the app. Sometimes manual code removal is required. Make backups of your theme any time you install or remove a new app in case anything goes wrong.
Use Shopify’s Free Search & Discovery App Instead of Heavy Filter Apps
It’s lightweight and won’t hurt vitals nearly as much as many third-party filter apps.
Run a Quick Test
Go to https://pagespeed.web.dev, enter your homepage URL, and look at the “Diagnostics” section. Google will literally tell you the biggest culprit.

When Scores Still Aren’t Perfect

Even after doing everything above, many stores end up with LCP around 2.0–2.7 s and CLS under 0.1 — which is actually considered “Good” by Google for real-world Shopify stores. Perfect 90–100 scores are rare once real content and apps are added, and that’s perfectly fine; Google cares far more about actual user experience than the lab score.

While we're happy to answer questions about these scores and will do our best to point you in the right direction, modifying your specific store in an effort to improve these metrics falls outside the scope of our included theme support. If you're serious about improving these metrics, we suggest hiring a Shopify developer who specializes in improving performance. SpeedBoostr is a solid recommendation for these services.