Site Speed Optimization:How to Improve Performance and SEO

From backlinks to technical SEO

In the previous guide, you learned how to build authority through high-quality backlinks. However, every link strategy loses effectiveness when the website receiving that traffic is slow.

You can publish the best content in your industry and earn the best mentions… but if your website does not load quickly, Google will struggle to keep your pages well positioned. Technical SEO is the foundation supporting everything else in the SEO journey.

What is technical SEO and why is it a fundamental pillar?

Although technical SEO covers many different aspects, they all pursue the same objective: making the work of search engines easier and providing the best possible experience for users.

The ranking of a web page therefore rests on three complementary pillars:

SEO

• Content
• Authority
• Technical SEO

Without content, there is nothing to show. Without authority, it is difficult to compete. Without technical SEO, search engines cannot interpret your website correctly and users do not stay on it.

How does speed affect your rankings?

The vast majority of users browse from a mobile phone, where the connection is not always perfect. When a visitor clicks your link and the page takes time to respond, two things happen:

The user leaves without reading

Nobody waits in front of a blank screen. The user goes back and visits your competitor’s website.

Google reduces your visibility

The search engine detects that users leave your page quickly and concludes that your website provides a poor experience.

In addition, a fast website generally produces more page views, longer visits and a greater probability of conversion.

How to measure your website’s speed with PageSpeed Insights

You do not need to guess what is wrong with your website. Free tools can analyse it and tell you exactly what needs to be fixed.

The reference tool is PageSpeed Insights, Google’s official platform.

The key metrics (Core Web Vitals)

When you analyse your website, you will see several metrics marked with colours according to their performance:

• Green (good): your website meets Google’s recommended standards.
• Yellow (needs improvement): there is room for optimisation, but the website remains usable.
• Red (poor): there is a priority technical problem that you need to correct.

Metric	What it measures
LCP	The time needed to display the largest element on the screen, such as the main image or heading.
INP	How quickly the website responds when the user clicks a button.
CLS	Movement of images or text while the page loads.
TTFB	The speed of your hosting, measured by the server response time.

How to read PageSpeed recommendations

The tool divides its advice into two main groups so that you know where to begin:

Opportunities

These are the priority actions. Applying these improvements will have a direct and immediate effect on your website’s speed, for example by reducing image weight.

Diagnostics

This section provides additional technical information about the page’s structure. It does not always require immediate changes, but it helps you understand how Google reads your website.

PageSpeed Insights tutorial, step by step

• Open the tool: go to pagespeed.web.dev.
• Enter your URL: paste the address of your home page or a specific article.
• Select the Mobile tab: focus on the mobile score, which is the one Google prioritises for ranking.
• Review the Opportunities section: note the priority recommendations marked in red and yellow.

How to solve the main performance problems in WordPress

PageSpeed will display a list of recommendations. In WordPress, nearly all warnings can be addressed by working on these five fundamental points.

Heavy images are the primary reason a website becomes slow.

Use modern formats

Save or convert your images to WebP. It weighs much less than traditional JPEG or PNG while retaining the same quality.

Reduce their size before uploading

Run your images through free tools such as TinyPNG before uploading them to your website to reduce their weight by more than 70% without losing sharpness.

Enable lazy loading

Images are downloaded only when the user scrolls down to where they appear.

Every time a visitor enters your website, WordPress retrieves the text and images from the database to build the page from scratch. This takes time.

The cache stores a fixed HTML “snapshot” of your page and shows it directly to the user. Loading becomes almost instantaneous.

Without caching

User

→

Server

→

Database

→

Generate HTML

→

User

Slow

With caching

User

→

Ready-made static HTML copy

→

User

Fast

Visual themes and page builders add design files and functions that can slow down page loading.

• Minify the code: remove spaces and unnecessary information from these files so that they weigh less.
• Delay what is not urgent: load secondary functions at the end so that the text and main image appear first.

If your server is in Spain and a user connects from Argentina, the data has to travel thousands of kilometres, adding an unavoidable delay.

A CDN solves this problem by storing copies of your images and files on servers distributed around the world, then delivering them from the point closest to the user.

In WordPress, less can be more. The point is not to install the smallest possible number of plugins, but to use only those that genuinely add value to the project.

Review your installed plugins periodically and ask yourself whether they still add value. In many cases, removing an unnecessary plugin improves performance more than installing a new one in an attempt to optimise speed.

Quick summary: from metric to solution

Use this table to connect the PageSpeed diagnosis with the practical solution in WordPress:

If PageSpeed shows…	The problem generally comes from…	Recommended solution
High LCP (slow main content)	Heavy images or no cache	Compress images in WebP format and enable a caching plugin.
High INP (delay after a click)	Too much JavaScript or heavy plugins	Minify the code, delay scripts and remove unnecessary plugins.
High CLS (content moves)	Images without dimensions or slow fonts	Define the width and height of images, then optimise the fonts.
High TTFB (slow server response)	Insufficient hosting or no cache	Enable page caching or consider changing hosting provider.

How to optimise your website for mobile devices

Most web traffic comes from mobile phones. For this reason, Google no longer judges your website by its desktop version, but applies Mobile-First Indexing: it evaluates and ranks your website primarily from its mobile version.

Key points to check on a phone screen

• Text size: the content must remain readable without zooming.
• Space between buttons: links and buttons must be separated enough to tap with a finger without making a mistake.
• No overflow: nothing should extend beyond the screen or force the user to scroll horizontally.
• Be careful with pop-ups: full-screen pop-ups inconvenience users and are penalised by Google.

Technical SEO for AI-powered search engines (GEO)

The optimisations you have just seen do not only help Google. They also make it easier for artificial-intelligence systems such as ChatGPT and Perplexity to access, understand and cite your content.

A fast, well-structured website is the first step towards gaining visibility in AI.

Allow access to AI crawlers

Make sure that your security plugins or server are not accidentally blocking AI crawlers such as OAI-SearchBot or PerplexityBot.

Make sure your content is accessible in HTML

AI-powered search engines read the page’s HTML code directly. If your main text appears only after complex JavaScript scripts are executed, some crawlers will not see it. In WordPress, content is generally accessible by default when you use standard editors such as Gutenberg or themes such as Divi.

Add structured data (Schema)

Structured data consists of invisible labels that tell search engines what type of content is on your website, for example an article, recipe or product.

What about the llms.txt file?

The llms.txt file is a recent proposal for summarising a website’s content for AI systems. It is not currently an essential standard, and having one does not replace good HTML or correct Schema configuration.

Quick technical SEO checklist

Before considering a page optimised, review this checklist in the order used in the module:

• The images are compressed and use WebP format.
• The caching plugin is active and working.
• No unnecessary plugins are installed.
• PageSpeed Insights shows no critical errors in red.
• The mobile version is perfectly readable without horizontal scrolling.
• Structured data (Schema) is enabled through a plugin.
• AI crawlers are not blocked by robots.txt or a security plugin.

Summary and next step

The objective is not to score 100 out of 100 in PageSpeed Insights, but to build a fast, stable and easy-to-use website for both people and search engines.

Technical SEO consists of removing the obstacles that make the work of search engines and users’ navigation more difficult. By optimising images, enabling caching and ensuring that your website works well on mobile, you have built the foundation on which the rest of your strategy will operate.

Next guide: SEO Tracking: How to Measure and Improve Your Results.

Previous step

4. Backlinks

You are here

5. Technical SEO

Next step

6. SEO tracking

Frequently asked questions about speed and technical performance