How to Check Your Website Speed (Core Web Vitals)

Your website might be slow and you don't even know it. You're on a fast computer with a great internet connection, so everything loads fine for you. But your visitors on mobile? They might be waiting five seconds for your page to appear. Here's how to check your website speed and actually fix what's wrong.

What Are Core Web Vitals?

Core Web Vitals are three specific metrics Google uses to measure your site's user experience:

• LCP (Largest Contentful Paint) — how fast the main content loads. Should be under 2.5 seconds.
• INP (Interaction to Next Paint) — how fast your site responds to clicks and taps. Should be under 200 milliseconds.
• CLS (Cumulative Layout Shift) — how much the page jumps around while loading. Should be under 0.1.

Google confirmed these are ranking factors. If your Core Web Vitals are bad, your search rankings can suffer. So yeah, checking your website speed is worth the two minutes it takes.

How to Run a Speed Test

Enter your URL into the website speed audit tool. It loads your page and measures everything — load time, Core Web Vitals scores, resource sizes, and request counts. You get a clear score plus specific things to fix.

The tool tests both mobile and desktop performance separately, which matters because most sites perform very differently on each. Your desktop score might be 90 while your mobile score is 45.

Common Issues and How to Fix Them

The most frequent problems I see when running speed audits are large unoptimized images (compress them or use WebP format), too many JavaScript files loading at once (defer what you can), no browser caching headers (add them to your server config), and render-blocking CSS (inline critical styles).

Honestly, images are the culprit like 80% of the time. I've seen single hero images that were 3MB when they could've been 150KB without any visible quality loss. Just compressing your images can double your speed score.

How Often Should You Test?

Check your site speed after any major change — new theme, added features, new plugins. Also worth checking monthly even if nothing changed, because third-party scripts (ads, analytics, chat widgets) can slow things down over time without you noticing.

Want to see how fast your site really is? Try it free →