How slow is too slow?
As a rule of thumb, the main content of a page should appear within 2.5 seconds on a typical mobile connection. Beyond that, more visitors give up before the page finishes loading, and mobile visitors are the least patient. If your site feels slow to you on a fast office connection, it's slower still for your customers.
1. Images that are too large
This is the number one cause. A photo straight from a camera or stock site can be 3–8 MB, when the same image at display size in WebP is often under 150 KB. Resize images to the largest size they're actually shown at, compress them, and use modern formats like WebP or AVIF.
2. Images that load all at once
Images below the fold don't need to load until the visitor scrolls. Adding loading="lazy" to those images can cut the initial download dramatically. Don't lazy-load the hero image, though: that one should load first. See our guide to lazy loading images.
3. Slow server response time
If your server takes more than about 600 ms to start sending a page (time to first byte), everything else waits. Common causes are cheap shared hosting, no page caching and slow database queries. Page caching or a CDN usually fixes it. Read fixing slow server response.
4. No text compression
HTML, CSS and JavaScript compress extremely well. Enabling Gzip or Brotli on your server typically shrinks them by 60–80%, and it's often a single setting. See enabling compression.
5. Too many plugins and scripts
Every plugin, tracking pixel, chat widget and social embed adds JavaScript the browser has to download and run. Audit what's installed and remove anything that isn't earning its place. This is the biggest fix for a poor INP score.
6. Render-blocking CSS and JavaScript
Scripts and stylesheets in the page head block the browser from showing anything until they've loaded. Add defer or async to scripts that don't need to run immediately, and keep critical CSS small.
7. Web fonts loading badly
Several font families, each in multiple weights, can add hundreds of kilobytes. Limit yourself to the weights you use, self-host where possible, preload the main font file and use font-display: swap so text appears straight away.
8. No browser caching
Without cache headers, returning visitors download your logo, CSS and scripts again on every page. Set long cache lifetimes for static files that rarely change.
9. Redirect chains
A link that goes http → https → www → final URL makes the browser do several round trips before it starts loading anything. Point links and redirects straight to the final URL.
10. No CDN for a global audience
If your server is in one country and your visitors are worldwide, every request travels a long way. A content delivery network serves files from a location near each visitor.
How to find out exactly what's slowing your site down
Guessing is slow. A website speed test shows which images are oversized, which scripts block rendering and how long your server takes to respond. Fix the biggest item first, test again, and repeat.
For the metrics behind all of this, read Core Web Vitals explained, or test your website speed for free.
Frequently asked questions
What is the most common reason a website is slow?
Oversized images. Uncompressed photos that are much larger than their display size are the most common cause of slow page loads, followed by slow hosting and too much JavaScript.
How can I check my website speed for free?
Use a free website speed test such as Pagelyt or Google PageSpeed Insights. Enter your URL and you'll get load-time metrics plus a list of specific issues to fix.
Does website speed affect SEO?
Yes. Page speed and Core Web Vitals are Google ranking signals, and slow pages also have higher bounce rates, which reduces conversions.
What is a good page load time?
Aim for the main content to appear within 2.5 seconds (a good Largest Contentful Paint) and for the page to respond to taps within 200 milliseconds.
Will changing hosting make my website faster?
It can, if your server response time is slow. If the slowness comes from large images or heavy scripts, better hosting alone won't fix it. Test first to find the real cause.