Technical SEO for eCommerce: Site Speed and Mobile Performance

Introduction

Technical SEO is capable of many things, but mainly, it keeps your store discoverable, fast, and functional. It’s the foundation that lets your content, products, and rankings do their job. This guide focuses on two key areas that move the needle: site speed and mobile optimisation. We’ll show you what to prioritise, how to fix common issues, and what tools to use.

Why Technical SEO Matters for eCommerce

If your goal is to be found and connect with the right audience, keyword choice is only part of the job. Your site’s technical setup decides whether your content can actually be discovered, stored, and ranked by search engines. 

Think of it as the foundation. If it’s unstable, the best keyword plan in the world won’t hold up.

Crawlability

Googlebot can’t buy your products, but it can visit every page it’s allowed to. If it spends time on the wrong ones, your important content might be missed. 

Avoid filters that create endless, useless URLs, duplicate page versions and orphaned pages with no links pointing to them

Indexing

If your products aren’t indexed, they might as well not exist in search. 

Keep things clean with:

• Accurate sitemaps
  
  
• Correct use of canonical tags
  
  
• A robots.txt file that isn’t blocking key pages
  
  

Speed

People hate waiting. So does Google.

A slow-loading page means higher bounce rates and lower rankings. To avoid this, compress images, minimise scripts, and use a reliable hosting setup.

Mobile-first indexing

Google now judges your site by its mobile version. If your mobile site is slow, cluttered, or broken, your rankings will take a hit, even if your desktop site is perfect. Test your mobile layout regularly and fix issues before they cost you visibility.

Technical SEO might not feel as exciting as content creation, but without it, your content has fewer ways to reach the people who are interested. A sound setup lets search engines find, understand, and rank your pages so your keyword strategy can actually work.

This stuff directly impacts revenue. Fast, crawlable, and mobile-friendly sites convert better. That’s what we aim for and you should too. 

Speed First: The Technical Priority That Pays

Compress and Optimise Images

Heavy images are still one of the biggest reasons eCommerce pages load at a snail’s pace. Every extra second can mean lost sales, frustrated shoppers, and lower search rankings.

The good news: image weight is an easy problem to fix.

Compress before uploading by starting with a smaller file size. Free tools like ImageOptim, TinyPNG, or Squoosh can cut image weight by 50–80% without noticeable quality loss. Make this part of your upload routine. 

Damson Madder focused on long-tail SEO and specific categories to compete with larger retailers. Their efforts included optimising images and mobile performance, resulting in a 558% increase in clicks through to product pages and a 410% increase in clicks through to collection pages.

 By improving site speed and mobile usability, they were able to enhance user engagement and conversion rates. Read the full case study.

Switch to modern formats

Formats like WebP or AVIF deliver the same visual quality as JPGs or PNGs but at a fraction of the size. Many browsers now support them, and most CMS platforms can convert automatically.

Lazy-load images below the fold

There’s no need to load every single image at once. Lazy loading delays the loading of images that aren’t visible yet, so the initial page view appears faster.

Clean Up CSS and JavaScript

 Bloated CSS and JavaScript slow your site, hurting clicks, conversions, and SEO.

• Remove unused code: Tools like PurgeCSS or UnCSS strip leftover styles and scripts.
  
  
• Minify files: Tools like cssnano (CSS) and Terser (JS) remove extra spaces and characters.
  
  
• Load scripts asynchronously: Use async or defer so scripts don’t block rendering.
  
  
• Inline above-the-fold CSS: Include only the CSS needed for the initial visible area.
  
  

Optimising CSS and JS improves Core Web Vitals, especially Largest Contentful Paint (LCP), making your site feel faster and keeping shoppers engaged.

Fix Server and Caching Issues

 Slow server response is a major performance bottleneck, directly affecting Time to First Byte (TTFB) which is the time it takes a browser to receive the first bit of data.

 A high TTFB makes your site feel unresponsive before the page even starts loading.

• Enable HTTP compression: Use gzip or Brotli to shrink files before sending them to browsers; Brotli works especially well for HTML, CSS, and JS.
  
  
• Serve content via a CDN: CDNs like Cloudflare or Fastly deliver cached content from servers closest to users, reducing latency.
  
  
• Set long cache expiry headers: Let browsers store static files like images, CSS, and JS locally to avoid repeat downloads.
  
  

Lower TTFB speeds up every aspect of page load, boosts Core Web Vitals, and creates a smoother shopping experience for your customers.

Use Speed Testing Tools the Right Way

Website speed testing isn’t a one-and-done job. Performance changes over time with new plugins, design tweaks, or even third-party scripts, can slow things down. Regular testing helps you spot problems early and measure whether your fixes are actually working.

Tools worth using:

• Google PageSpeed Insights combines lab data with real-world Core Web Vitals from the Chrome User Experience Report. This is great for seeing how actual users experience your site.
  
  
• Lighthouse (in Chrome DevTools) runs in your browser and provides detailed audits on performance, accessibility, SEO, and more.
  
  
• GTmetrix lets you track performance over time, so you can see trends and compare results from different optimisation efforts

Metrics to focus on

• First Contentful Paint (FCP): Measures how quickly the first piece of content appears.
  
  
• Largest Contentful Paint (LCP): Tracks how long it takes for the main content to appear.
  
  
• Cumulative Layout Shift (CLS): Measures how stable your page layout is while loading.
  
  
• Time to Interactive (TTI): Shows how long it takes before a page is fully usable.

Make testing part of your workflow

After every optimisation, re-test your site to confirm the change improved performance. Keep a record of your results so you can see what’s moving the needle and what’s not.

Consistent testing keeps your site fast and user-friendly, which helps both your customers and your search rankings.

Mobile SEO: Build for Real Users, Not Just Bots

• Responsive Design Basics

• Mobile-first design isn’t just a nice touch. It’s how Google indexes and ranks your site. Since mobile traffic often outnumbers desktop,a poor mobile experience can hurt both your rankings and conversions.

• Use modern responsive layout tools

• CSS Grid and Flexbox make it easier to create layouts that adapt to any screen size without breaking. These tools let you rearrange elements fluidly instead of relying on clunky fixed-width designs.

• Set comfortable tap targets

• Buttons, links, and interactive elements should be at least 48px in height and width. Anything smaller risks frustrating users who can’t tap accurately on smaller screens.

• Avoid mobile design traps

• No horizontal scrolling. It forces users to drag the screen side-to-side just to read or shop. Skip fixed-width elements that don’t adapt to narrow viewports. Limit pop-ups and modals that block content or require precise tapping to close.

• Design for touch interactions

• Mobile users tap, swipe, pinch, and scroll in quick bursts. Your layout should respond smoothly without mis-clicks or lag. Test your site on actual devices, not just desktop emulators, to catch usability issues.

• A mobile-first approach makes your site more accessible, keeps shoppers engaged, and aligns with how Google evaluates your pages for search.

• TouchNote, a personalised card brand, saw a 202% increase in position #1-3 keyword rankings in less than a year. By working closely with their team, we tackled key international and technical SEO challenges, including mobile optimisation, which helped improve both search visibility and user experience. 

Explore the full case study here.

Prioritise Mobile Performance

Mobile users often have slower connections and older devices.

• Load only critical scripts and defer the rest.
  
  
• Avoid auto-playing videos or massive banners.
  
  
• Optimise your critical rendering path so mobile browsers can render content fast.
  
  

This isn’t just about speed, it’s about usability. A mobile user waiting 4 seconds for a product page won’t wait around.

Crawlable Mobile Structure

• Use the same URLs and content for mobile and desktop (responsive is better than m-dot).
  
  
• Avoid deep directory nesting. Keep product URLs clean and direct.
  
  
• Use breadcrumb navigation and schema for better clarity and structure.
  
  

If you’re running separate mobile URLs, make sure you’ve configured rel="alternate" and canonical tags properly.

Site Structure and Schema Markup

Structure Your Store Logically

Every product should be reachable in 3 clicks or fewer from the homepage.

• Structure: /category/ → /subcategory/ → /product/
  
  
• Use internal links to connect related products and categories.
  
  
• Add breadcrumbs for better navigation and crawl context.
  
  

A flat, logical structure helps both users and bots.

Robots.txt and XML Sitemaps

Robots.txt can block bots and guide them to perform various tasks.

More specifically, a robots.txt file tells search engine crawlers which URLs the crawler can access on your site. This is used mainly to avoid overloading your site with requests; it is not a mechanism for keeping a web page out of Google. To keep a web page out of Google, block indexing with no index or password-protect the page.

• Block filter and sort parameters (e.g., ?sort=price_asc) that create duplicate pages.
  
  
• Don’t block resources (JS/CSS) needed to render your site.
  
  
• Keep XML sitemaps updated with all live products and categories. Remove out-of-stock or deleted pages.
  
  

Submit your sitemap to Google Search Console to speed up discovery and indexing.

Use Structured Data

Schema markup gives search engines extra context about your content.

Use:

• Product schema: name, description, price, availability, and ratings.
  
  
• Breadcrumb schema: to show hierarchy in SERPs.
  
  
• Review schema: to display star ratings.
  
  

Validate your structured data using Google’s Rich Results Test or Schema.org validator.

Schema doesn’t directly boost rankings, but it increases CTR by enhancing your listings.

Regular Audits and Ongoing Maintenance

Technical SEO isn’t a one-off job. eCommerce stores change constantly, and so should your audits.

Tools for Monitoring

Monitoring your site’s technical health requires the right tools.

Here are some essential ones for eCommerce sites:

Screaming Frog

Screaming Frog is a powerful crawler that analyses your entire website, helping you identify issues such as:

-        Broken links (404 errors)

-        Missing or duplicate meta tags

-        Duplicate content

-        Redirect chains

This is important as catching these issues early prevents search engines from running into errors that can affect rankings and ensures users don’t encounter frustrating dead ends.

Sitebulb

Sitebulb offers visual site audits and in-depth analysis of internal linking structures.

It helps you:

-        Understand the flow of link equity across your site

-        Spot orphaned pages that aren’t linked internally

-        Get visual dashboards that make complex technical issues easier to interpret

Internal linking is critical for SEO, helping both users and search engines navigate your site efficiently.

Google Search Console (GSC)

GSC provides insights directly from Google, including:

-        Crawl errors

-        Indexing issues

-        Core Web Vitals performance

-        Security alerts

It gives you a direct line to Google’s view of your site, enabling you to fix issues that could impact search visibility and user experience.

Set Up Automated Alerts

Automation is your friend for staying on top of technical issues without manually checking daily.

Set up alerts for:

-        Crawl spikes or sudden drops

-        Broken links or 404 errors

-        Drops in traffic or Core Web Vitals metrics’

Proactive monitoring allows you to react quickly to problems before they escalate, minimising downtime and preserving user experience. Using these tools consistently helps you maintain a technically sound eCommerce site. Regular audits combined with automated alerts ensure that your site evolves healthily alongside your business, preventing small issues from becoming major SEO problems.

Maintenance Schedule

This approach ensures your technical SEO stays healthy and proactive, rather than reactive.

Avoid These Common Technical Mistakes

Even the most well-designed e-commerce sites can suffer from technical issues that quietly sabotage performance, usability, and search visibility. These problems are surprisingly common, but fixing them can give you a noticeable edge over competitors.

 Here’s what to watch out for:

Bloated Images or Scripts

Large images and heavy scripts are among the most common performance killers. Every extra kilobyte slows page load, frustrates users, and can even harm search rankings. Slow-loading pages increase bounce rates, especially on mobile. Users expect pages to load in 2–3 seconds, and anything longer can cost conversions.

To fix this, compress and resize images appropriately for web use, use modern formats like WebP for faster loading, audit scripts and remove unnecessary ones, or load them asynchronously.

Mobile Tap Targets Too Small

Buttons, links, and interactive elements that are too small make your site frustrating to navigate on mobile devices. Users may miss taps, leading to frustration or abandoned carts. Mobile-first indexing means Google evaluates your mobile experience heavily. 

Poor usability can impact rankings and, more importantly, sales.

In order to avoid this, ensure buttons are at least 44x44 pixels with enough spacing. Test all forms and navigation elements on multiple screen sizes. Use clear, distinct visual cues to show what’s clickable.

Crawl Traps in Faceted Navigation

Faceted navigation (filters by size, color, price, etc.) can create “crawl traps” which are endless combinations of URLs that search engines try to crawl but offer little unique value. Crawl traps waste crawl budget, meaning search engines may not index your important pages efficiently.

To fix this, use noindex or canonical tags on low-value faceted pages, limit the number of filter combinations available to crawlers and monitor your site’s crawl stats in Google Search Console.

No Structured Data

Structured data (like Schema.org markup) helps search engines understand your content and can make your listings eligible for rich results, such as product ratings, prices, and availability. Without structured data, you miss opportunities to stand out in search results and attract more clicks.

To fix it, add product, review, and breadcrumb markup where relevant. Test structured data using Google’s Rich Results Test and keep your markup up to date with your catalog changes.

Duplicate Content

Duplicate content often appears due to multiple product variations, category overlaps, or paginated pages. This can confuse search engines about which page to rank. Search engines may dilute ranking signals, leading to lower visibility for important pages.

To fix it, implement canonical tags pointing to the preferred version and also consolidate similar pages where possible. 

Lastly, avoid indexing low-value or near-duplicate pages.

Avoiding these common technical mistakes is one of the fastest ways to gain an advantage over competitors. Small fixes in images, scripts, mobile usability, crawl management, structured data, and duplicate content can deliver big results in traffic, rankings, and conversions.

Final Checklist

Before we call it done at StudioHawk, we always:

• Run a speed audit (PageSpeed Insights, GTmetrix, Lighthouse)
  
  
• Compress images, defer scripts, and enable caching
  
  
• Ensure your mobile experience works on real devices
  
  
• Check structured data with a validator
  
  
• Submit updated sitemaps and monitor GSC
  
  
• Set a schedule for regular audits
  
  

It’s not glamorous work, but it pays off.

Need Help?

If you want a hand with audits, schema markup, CDN setup, or a site speed overhaul, let’s talk. Clear technical SEO means faster pages, better rankings, and fewer headaches.

Not sure where to start? If you’re looking for expert guidance to build a content strategy that delivers real results, speak to the team at StudioHawk. We'll work with you to create and maintain content that remains relevant, useful, and optimised for sustainable growth.