Speed is one of the few things every visitor notices. A slow page loses people before they read a word, and on phones with weaker connections the effect is larger. Faster sites tend to convert better, and page experience is one of the signals search engines consider. The good news is that most slow sites share the same few problems, and fixing them does not usually require a rebuild.
This guide explains how to measure speed, then walks through fixes in rough order of impact.
Measure first
There are two kinds of measurement:
- Field data: how fast the site is for real visitors, collected by browsers. Google's PageSpeed Insights shows this for sites with enough traffic, as does search console.
- Lab data: a test run from one location on one simulated device. Useful for finding causes and testing fixes, but not the full picture.
Test your home page, your top landing pages and a typical inner page, on mobile settings. Note the results so you can compare after each fix.
Understand Core Web Vitals
Google's Core Web Vitals are three measures of user experience:
- Largest Contentful Paint (LCP): how quickly the main content appears. Good is 2.5 seconds or less.
- Interaction to Next Paint (INP): how quickly the page responds to taps and clicks. Good is 200 milliseconds or less.
- Cumulative Layout Shift (CLS): how much the layout jumps while loading. Good is 0.1 or less.
These are measured at the 75th percentile of visits, so most visitors, not just those on fast connections, should have a good experience. Latency between the visitor and the server affects all three.
1. Fix images
Images are the heaviest part of most pages and the easiest win:
- Use modern formats such as WebP or AVIF, which are often much smaller than JPEG or PNG.
- Serve the right size for each screen, using responsive image markup, rather than one large image for everyone.
- Compress images. Most can be much smaller with no visible difference.
- Lazy-load images below the fold, but not the main image at the top.
- Set width and height so the layout does not jump as images load.
2. Cut and delay scripts
Third-party scripts, such as chat widgets, trackers, ad tags and social embeds, often slow pages more than anything else and hurt responsiveness. List every script on the site and ask whether it earns its place. Remove what you do not use. Load the rest after the page is usable, or only on pages that need them. For your own scripts, send less code and split it so each page loads only what it needs.
3. Load fonts carefully
Web fonts can delay text or cause it to jump. Use fewer font families and weights, host fonts on your own domain, use modern compressed formats and set text to show immediately with a fallback font while the web font loads. Preload the one or two fonts used above the fold.
4. Trim CSS
Large style sheets block the page from appearing. Remove unused styles, which build tools can do automatically, and keep the critical styles small. Avoid loading separate style sheets for plugins or widgets on pages that do not use them.
5. Cache everything you can
- Browser caching: set long cache times for images, fonts, scripts and styles, with file names that change when the content changes.
- Page caching: serve ready-made pages instead of building them on each visit, where content allows.
- Server caching: cache database queries and expensive work on the server.
6. Use a content delivery network
A content delivery network stores copies of your files on servers around the world, so visitors download them from somewhere nearby. It reduces latency, absorbs traffic spikes and often adds compression and modern protocols. For sites with visitors in many regions, it is one of the simplest improvements.
7. Choose the right hosting
Cheap shared hosting can make every page slow, no matter how well it is built. A good managed host or a VPS with enough memory and a modern PHP or Node version gives the site room to respond quickly. Measure the server response time; if it is slow even for simple pages, hosting or server code is the problem. See cloud hosting.
8. Stop layout shifts
Layout shifts happen when content moves after it appears, often because an image, ad or banner loads late and pushes text down. Reserve space for images and embeds, avoid inserting banners above content after load and make sure fonts do not change size dramatically when they swap.
9. Improve responsiveness
A page that looks loaded but does not respond to taps feels broken. The cause is usually heavy JavaScript running on the main thread. Reduce script size, break long tasks into smaller ones, delay non-essential work and remove scripts that run on every interaction without need.
10. CMS-specific fixes
On WordPress and similar systems, the main culprits are heavy themes, too many plugins and missing caching. Use a lightweight theme, remove unused plugins, add a caching plugin or host-level caching and optimize images on upload. For content-heavy sites that need top speed, a headless CMS with a static or cached front end is an option. See WordPress development.
Videos and embeds
Embedded videos, maps and social posts load a lot of code before anyone presses play. Replace them with a lightweight preview image that loads the real embed only when clicked. For background videos, keep them short, compressed and muted, or use a still image on phones. Each embed you delay makes the page lighter for everyone who never uses it.
What to fix first
- Oversized images, especially the hero image.
- Unneeded third-party scripts.
- Missing caching and compression.
- Slow hosting.
- Fonts and CSS.
- Layout shifts and responsiveness details.
Keeping it fast
Sites get slower over time as scripts, plugins and images pile up. Set a simple budget, such as a maximum page weight and number of scripts, and check speed monthly and after every significant change. Make speed part of the review for new features and campaigns.
An example
A service business site took several seconds to show its main content on phones. The hero image was a large PNG, the page loaded five tracking and chat scripts and there was no caching. Converting images to WebP at proper sizes, removing two unused scripts, delaying the chat widget and enabling caching brought the main content into the good range for most visitors, with no redesign. This is illustrative.
Related guides
Speed is often part of a bigger project. See the website redesign checklist, SEO basics for new websites and progressive web apps explained.
Speed work pays off twice: visitors get a better experience today, and the site becomes easier and cheaper to run. Start with the biggest problem you find, measure the change and move to the next one. Small, steady fixes usually beat one large project.