How to Speed Up a Website: 12 Practical Fixes and Core Web Vitals Explained
Why is your site slow? How to read your Core Web Vitals and how to speed up your website with 12 fixes, from images and fonts to caching and the server.
Try opening your website on your phone, on mobile data, as if you had never visited before. How long does the screen stay blank? Does the layout jump once the text appears? When you tap a button, does the page respond straight away? That is the experience your potential customers have every day.
For many businesses, website speed feels like a technical detail. In reality it is the first thing that decides whether a visitor stays on your site. The good news is that most slow sites are slow for the same handful of reasons, and those reasons can be fixed. This article first looks at why your site is slow, then at how Google measures speed, and finally at 12 fixes you can apply.
Why is your website slow? The 6 most common causes
These problems turn up almost every time we look at a slow site:
- Oversized images: Photos uploaded straight from a camera or design tool, several megabytes each.
- Heavy themes and plugins: All-in-one themes that load dozens of features nobody uses, and plugins that duplicate each other's work.
- Third-party scripts: Chat widgets, ad pixels, maps, videos and social media embeds.
- A slow server: Crowded, cheap shared hosting or an outdated PHP version.
- No caching: The page is built from scratch on every single visit.
- Web fonts: Several font families loaded along with weights that are never used.
How does website speed affect sales?
The internet is full of percentages about the impact of speed on sales, and the source of most of them is unclear. You do not need numbers to see the following; anyone can confirm them from their own experience:
- If a visitor presses the back button before the page loads, they never saw your site. For a visitor who came from an ad, that is a click you paid for and wasted.
- Slow product pages push users towards the other tab where they are comparing prices.
- Buttons that shift while the page loads cause mis-taps and frustration, and leave an impression that your brand is careless.
- Google takes page experience into account. Between two pages with similar content, the faster one can move a step ahead.
In short, speed is a multiplier that decides whether your ad budget and SEO work pay off. We look at the advertising side in our Google Ads guide.
What are Core Web Vitals? LCP, INP and CLS
Google assesses page experience with three core metrics. These are the Core Web Vitals, and the values are collected from real visitors' browsers.
| Metric | What does it measure? | Good | Poor |
|---|---|---|---|
| LCP (Largest Contentful Paint) | How long it takes for the largest image or text block on the page to appear | 2.5 seconds or less | Over 4 seconds |
| INP (Interaction to Next Paint) | How quickly the page responds to clicks, taps and key presses | 200 milliseconds or less | Over 500 milliseconds |
| CLS (Cumulative Layout Shift) | How much content moves unexpectedly while the page loads | 0.1 or less | Over 0.25 |
INP replaced the older FID metric in March 2024. The assessment is based on the 75th percentile of visits, which means your page has to perform well not just on fast connections but also on below-average devices. For the technical details, Google's Core Web Vitals page on web.dev is a good reference.
How to test website speed: PageSpeed Insights and Search Console
Before you start optimising, record where you stand. Otherwise you will not know whether a change made any difference.
PageSpeed Insights
Enter a page URL into PageSpeed Insights and you will see two kinds of data. The top section shows real-user data, if your site has enough traffic. The score below it comes from a single lab test and is meant for diagnosing problems. Focus on the mobile result, as that is probably where most of your visitors come from.
Google Search Console
The Core Web Vitals report in Search Console shows your whole site rather than a single page, and groups URLs as "Good", "Needs improvement" and "Poor". Pages built on the same template usually share the same problem, so this report tells you where to start.
Start with images and fonts: fixes 1-5
1. Serve images at the right size
Uploading a photo at 4,000 pixels wide when it will be displayed at 800 pixels is the most common enemy of speed. Resize each image to the largest size at which it appears, and offer several sizes for different screens (srcset). That way a phone does not have to download a huge image prepared for desktop.
2. Switch to WebP and AVIF
WebP and AVIF deliver the same visual quality as JPEG and PNG at a much smaller file size. All current browsers support WebP, and the great majority support AVIF. On WordPress there are plugins that handle the conversion; on a custom-built site it can happen automatically at upload.
3. Use lazy loading
Images further down the page should not load until the user scrolls to them. Adding loading="lazy" to the image tag is enough. There is one exception: the main image at the top of the page should not be lazy-loaded but given priority. Otherwise your LCP gets worse.
4. Set image dimensions to prevent layout shift
If width and height are not defined for images, the browser cannot reserve space, and when the image loads the text below it jumps down. That directly hurts CLS. The same applies to banners and cookie notices that load late.
5. Simplify your fonts
Two font families, with only the two or three weights you actually use, are enough for most sites. Serve fonts from your own server where possible, in WOFF2 format, and use font-display: swap so text stays visible before the font loads. If you publish in several languages, check that the font files include every character you need, such as Turkish ğ, ş and ı or German umlauts.
Then code, server and caching: fixes 6-12
6. Remove unnecessary plugins and scripts
For every plugin and third-party script on your site, ask: who used this in the last three months, and what did it do? Old analytics tags, pixels left over from past campaigns and chat boxes nobody answers slow the page down for nothing. Defer the ones you do need so they run after the page has loaded.
7. Minify and defer CSS and JavaScript
Stripping spaces and comments from code files (minification) makes them smaller. More important is deferring JavaScript that is not needed for the first view, using defer or async. The browser then shows the content first and runs the code afterwards. This step also improves INP.
8. Turn on compression
When your server sends HTML, CSS and JavaScript compressed with Gzip or Brotli, the amount of data transferred drops sharply. On most servers this is a single setting, but do not assume it is on. Check.
9. Set up caching properly
There are two kinds of cache. A page cache stores a ready-made copy of a dynamically generated page so the database is not queried on every visit. A browser cache keeps files such as images, CSS and JavaScript on the visitor's device, making the second page view much faster.
10. Improve hosting and server response time (TTFB)
TTFB is the time it takes for the browser to receive the first byte from the server. If it is high, every other improvement is capped. Moving from crowded shared hosting to a stronger plan, running a current PHP version and cleaning up the database all reduce TTFB. Server location matters too: hosting close to where most of your visitors are makes a difference.
11. Use a CDN
A content delivery network (CDN) copies your site's static files to servers around the world and serves visitors from the nearest point. For sites with international visitors, especially hotels and exporters, a CDN is close to essential. Many CDNs also provide compression, image conversion and basic security protection.
12. Lighten video, map and social media embeds
An embedded video player or map loads hundreds of kilobytes of code even if nobody clicks on it. Showing a preview image first and loading the real player only when the user clicks (the facade pattern) gives the same experience at a fraction of the weight.
How to speed up a website: what to do first
Rather than trying all twelve fixes at once, work in this order:
- Record your current state in PageSpeed Insights and Search Console.
- Resize images and convert them to WebP or AVIF. On most sites, this is where the fastest and biggest gain lies.
- Remove plugins and scripts you do not use.
- Turn on caching and compression.
- If the site is still slow, look at the server side: TTFB and your hosting plan.
- Measure again after each step and note the result.
How to speed up a WordPress site: extra notes
A large share of corporate websites run on WordPress, and the causes of slowness on these sites are strikingly similar. In addition to the fixes above, check the following:
- Page builder overhead: Drag-and-drop page builders add a lot of extra code to every page. If you are building a new site, choose a lighter set-up; on an existing site, switch off modules you do not use.
- Plugin quality matters more than plugin count: Ten lightweight plugins can cause fewer problems than one heavy one. To find the plugin slowing the page down, disable them one by one on a staging site and measure.
- Database clean-up: Post revisions, tables left behind by deleted plugins and temporary data pile up over the years and slow down queries.
- Current PHP version: Check the PHP version in your hosting panel. An old version is slower and no longer receives security updates.
Speed is not a one-off job
Speeding up a site once is not enough. Every new campaign image, plugin and marketing script can slow it down again. Treat speed as a value you check regularly rather than a project with an end date. Looking at the Core Web Vitals report once a month lets you catch problems before they grow. Make it a habit to repeat the same measurement whenever you add a plugin or a campaign page, so you know immediately which change caused a problem.
Site speed is one part of a wider picture of site health. We explain how to assess it alongside SEO, security and mobile usability in our guide on how to audit a website. If you are wondering how your choice of platform affects speed, see our website builder vs WordPress vs custom comparison.
If you would rather not handle this yourself, Fietto Creative's digital continuity service keeps speed, SEO and technical maintenance under regular review. To see where your site stands today, run a free check with our website audit tool.
Frequently asked questions
Does website speed affect Google rankings?
Yes. Core Web Vitals are among the page experience signals Google uses. They are not decisive on their own, though: how relevant your content is to the search is still the most important factor. Speed makes a difference between pages of similar quality and directly affects whether visitors stay.
Why does my PageSpeed score change every time I test?
A lab test is affected by network and server conditions each time it runs, so a swing of a few points is normal. For a more reliable picture, look at the average of several runs and at the real-user data shown for the page.
How do I speed up a WordPress site?
Remove plugins you do not use, choose a lightweight theme, set up a caching solution, convert images to WebP or AVIF and make sure your PHP version is current. These steps bring a noticeable improvement on most WordPress sites.
How do I know if my website is fast enough?
The most solid indicator is your URLs sitting in the Good group of the Core Web Vitals report in Google Search Console. That report is based on the experience of real visitors.
