If you’ve spent any time checking your site performance in Google Search Console or PageSpeed Insights, you’ve probably seen the dreaded Core Web Vitals report.
It can feel like:
- “Largest Contentful Paint? What does that even mean?”
- “CLS is bad? But nothing moves!”
- “FID? My store is fine!”
Let’s slow down for a second.
Core Web Vitals matter because they measure real user experience, not just numbers. Slow pages don’t just frustrate customers, they damage conversions. If you work in e-commerce, you can use apps like Speedboostr to increase your Shopify store speed.
The good news? They’re improvable. And you don’t need to be a performance wizard to see gains.
Here’s how to tackle each one clearly and sensibly.
What Are Core Web Vitals? (Quick Primer)
Google focuses on three points:
- LCP (Largest Contentful Paint): How fast the main content loads.
- FID (First Input Delay): How soon your page becomes interactive.
- CLS (Cumulative Layout Shift): How stable the layout feels as it loads.
You want:
- LCP under ~2.5 seconds
- FID under ~100 milliseconds
- CLS is as close to zero as possible
Those numbers matter because fast, stable pages keep customers browsing and buying.
Speed Tip 1 — Get Serious About Your Images
Images are often the biggest problem for performance.
They might look clear, but they can also be huge in file size.
Here’s what you can do:
- Compress images before uploading.
- Use next-gen formats like WebP.
- Resize images to the actual display size.
Just fixing images usually moves LCP in the right direction.
Read: Optimize Your Store Images - SpeedBoostr Google Speed ‑ SEO
Every script you load adds time before the page becomes interactive.
Here’s what you can do:
- Delay non-critical scripts until after the page loads.
- Remove unused apps, especially ones that load scripts on every page.
- Avoid too many third-party embeds, like chat widgets, reviews, or trackers.
Less JavaScript often means faster FID.
Speed Tip 3 — Make CSS Lean and Mean
CSS controls how your site looks. But lots of CSS files can delay rendering.
A few ways to slim down CSS load:
- Inline only critical CSS needed for above-the-fold content.
- Defer the rest so it loads after the page displays.
- Remove theme styles you don’t use.
This helps both LCP and CLS.
Speed Tip 4 — Lock Down Layout Stability
Have you ever seen a button jump just as you try to tap it? Happens when elements load and shift others around.
That’s CLS.
To fix it:
- Reserve space for images and embeds (set width and height)
- Avoid inserting ads or banners above content after load
- Don’t inject content dynamically without a placeholder
Stable layout = happy users = low CLS.
Speed Tip 5 — Smart Caching and CDN Use
Caching is not sexy, but it works.
When repeat visitors come back, cached assets load instantly instead of re-downloading.
Shopify already uses a CDN for asset delivery, but you can also:
- Make sure your theme cache rules are optimal.
- Keep large assets versioned so updates don’t bust the cache.
- Avoid query strings that break CDN caching.
Better caching means faster repeat views and happier users.
Speed Tip 6 — Measure, Don’t Guess
You can’t improve what you don’t measure.
Use tools like:
- Google PageSpeed Insights
- Lighthouse
- Chrome DevTools
- Real User Monitoring
Look for:
- Slowest pages
- Largest files
- Scripts with high execution time
- Layout shifts
Track these over time. You’ll see real progress, not guesswork.
Bonus: Not All Themes Are Equal
Some themes are simply lighter than others.
If your theme loads lots of features you never use, you should clean up. Or a change.
A lean theme plus disciplined asset and script management moves all three Core Web Vitals in the right direction.
Conclusion
Improving Core Web Vitals isn’t a task that is done in one go. Your store evolves. You add features. You test ideas. All of that impacts speed.
The trick isn’t perfection.
It’s disciplined improvement.
Small wins stack up fast:
- Compress images.
- Tidy up JavaScript.
- Reserve layout space.
- Measure impact.
Do these consistently, and you’ll see customers stay longer, scroll more, and buy more often.
