Guide

Website speed and performance: the basics for business owners.

People leave slow pages, and search engines notice. Most slowness comes from a handful of ordinary causes, such as oversized images, too many scripts and unhelpful hosting. This guide explains what is measured, what usually goes wrong and how to check and improve your own site, without needing to read code.

Key takeaways

Test on a mid-range phone and a normal mobile connection, not your office computer.
Images, third-party scripts and web fonts are the usual culprits.
Three measures matter most: how fast the main content appears, how quickly the page responds and whether it jumps around.
Fast pages are simple pages: each addition has a cost.
Performance is kept, not achieved once. Re-test after changes.

What “fast” means: the three Core Web Vitals

Google publishes three measures of real-world page experience, called Core Web Vitals. A page is judged “good” on a measure when at least three quarters of real visits meet the threshold:

Loading: Largest Contentful Paint (LCP). How soon the main content, usually the biggest image or heading, appears. Good is 2.5 seconds or less.
Responsiveness: Interaction to Next Paint (INP). How quickly the page reacts when someone taps or clicks. Good is 200 milliseconds or less.
Visual stability: Cumulative Layout Shift (CLS). Whether things move while loading, so that a tap lands on the wrong button. Good is 0.1 or less.

Thresholds are set by Google and can be revised; check the current figures on web.dev. Speed is one of many factors that affect search results, and no score guarantees rankings.

The usual causes of a slow page

Oversized images. A photo straight from a camera can be many megabytes. Resize to the size shown, use modern formats and load images below the fold later.
Too many scripts. Chat widgets, analytics, advertising pixels, review badges and social buttons each add weight and delay. Keep only those that earn their place.
Heavy fonts. Chinese fonts are large. Use system fonts or a small, carefully chosen subset, and avoid loading many weights.
Slow hosting or no caching. A distant, overloaded or poorly configured server slows everything. A content delivery network can help.
Page builders and plugins that load their whole toolkit on every page.
Video and sliders at the top of the page, which are often the heaviest elements of all.
Layout that moves. Images and ads without reserved space push the text down as they load.

How to check your own site

Use a free testing tool such as Google's PageSpeed Insights. It shows measurements from real visitors where there is enough traffic, and a lab test, with suggestions.
Test your most important pages, not only the home page: a product, a booking or a contact page.
Test on mobile settings first, and, if you can, on a real mid-range phone over ordinary mobile data.
Test from where your customers are. A site that is quick in Hong Kong may be slow elsewhere.
Repeat a few times. Results vary. Look for patterns, not a single number.

A short improvement plan

Start with images. Compress and resize the largest ones. This alone often gives the biggest gain.
Remove what nobody uses. Old plugins, unused trackers and duplicate libraries.
Defer the rest. Load chat, video and analytics after the main content, or on request.
Reserve space for images, embeds and banners so the layout does not jump.
Check hosting and caching, and use a content delivery network where it helps.
Set a budget. For example, “the home page must stay under a set size”, and check it whenever content is added.

For how we think about the foundations, see websites and web apps.

Keep reading

Run through the launch readiness checklist before a go-live.

Frequently asked questions

What score should I aim for?

Aim for “good” on the three Core Web Vitals for real visitors, rather than a perfect lab score. A page can score 100 in a test and still feel slow, or the reverse.

Will a faster site improve my search ranking?

It can help, and it helps visitors and sales regardless. Speed is one factor among many, and nobody can promise a ranking.

Is a bilingual site slower?

Not by itself. Chinese fonts and double the images can make it heavier, so apply the same discipline to both languages and test both.

Is your site slower than it should be?

Send us the address. We will tell you what is slowing it down and what is worth fixing first.

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