Web Performance — Analysis of 900 Speed and Optimization Interventions Since 2018

Does your site take over 5 seconds to load? Are your PageSpeed scores in the red? Are your customers leaving before they even see your products? You're not alone. Since 2018, MonSiteBug has handled 900 performance and speed-related interventions — slow sites, terrible Core Web Vitals, overloaded servers, unoptimized databases.

This article is an exclusive study based on our real data. No theory: hard numbers from our 8,809 support tickets and concrete cases handled by our team.

Why performance has become critical

Since 2021, Google has integrated Core Web Vitals as an SEO ranking factor. A slow site loses positions, traffic, and sales. The three essential metrics:

• LCP (Largest Contentful Paint) — The rendering time of the largest visible element. Target: under 2.5 seconds.
• CLS (Cumulative Layout Shift) — The visual stability of the page. Target: under 0.1.
• INP (Interaction to Next Paint) — Responsiveness to user interactions (replaced FID in March 2024). Target: under 200ms.

Direct impact: According to Google, 53% of mobile visitors leave a site that takes more than 3 seconds to load. Each additional second of delay reduces conversions by 7%.

Performance request trends: 2018–2026

Performance optimization requests have seen consistent growth, reflecting the increasing awareness of the importance of speed:

Key point: The 2022 peak (159 tickets) coincides with the period when Google fully integrated Core Web Vitals into its algorithm. Merchants realized that speed was no longer a luxury but a necessity for their rankings.

The most common performance issues

Out of our 900 performance interventions, here are the most frequent causes of slowness we encounter:

1. Unoptimized images — The #1 problem

By far the most common cause of slow sites. Product images uploaded directly from the camera (3-5 MB each), without compression, without modern formats (WebP/AVIF), without lazy loading. Result: a catalog page weighing 15 MB instead of 1.5 MB.

• Conversion to WebP or AVIF (60-80% reduction without visible loss)
• Resizing to actual display dimensions
• Native lazy loading (loading="lazy") for off-screen images
• Using a CDN to serve assets from the nearest server

2. Module and plugin overload

The bane of PrestaShop stores and WordPress sites. Each module adds its own CSS and JavaScript files, SQL queries, and hooks. The accumulation ends up choking the site.

PrestaShop: the module trap

• Stores with 80+ active modules, half of which are unused
• Free or cheap themes that load everything, everywhere (slider on the product page, carousel on checkout...)
• Third-party statistics modules running heavy SQL queries on every page
• Poorly configured "cache" modules that slow down instead of speed up

WordPress: the plugin jungle

• Sites with 40+ plugins for basic functions
• Overloaded multipurpose themes (Avada, Divi) loading 500 KB of unused CSS
• Page builders (Elementor, WPBakery) generating monstrous HTML
• Misconfigured cache plugins that conflict with each other

3. Misconfigured server

A shared hosting plan for 3 euros a month will not handle an e-commerce store with 5,000 products and 200 simultaneous visitors. Here are the server optimizations we regularly perform:

• PHP-FPM instead of mod_php (30-50% performance gain)
• OPcache enabled and properly sized
• PHP 8.2+ — each major version brings 15-25% more performance
• Redis or Memcached for session and data caching
• Nginx as reverse proxy in front of Apache (or full replacement)
• gzip/brotli compression for HTTP
• Properly configured Cache-Control headers

4. Unoptimized database

PrestaShop and WordPress stores accumulate unnecessary data over time: logs, expired sessions, revisions, abandoned carts, data from uninstalled modules. The database grows and queries slow down.

• Table cleanup — Removing orphaned and obsolete data
• SQL query optimization — Adding missing indexes, rewriting heavy queries
• MySQL/MariaDB configuration — Tuning innodb_buffer_pool_size, query_cache, max_connections
• N+1 queries — A classic: 1 query per product instead of a single grouped query

The impact of anti-bot scripts on performance

A little-known but increasingly common problem: anti-bot protection scripts (reCAPTCHA, hCaptcha, anti-fraud solutions) that massively degrade performance. We have observed cases where:

• Google reCAPTCHA v3 loads 500 KB of JavaScript on every page, even when there is no form
• Cloudflare Under Attack Mode solutions left permanently enabled add 3-5 seconds of delay
• Fraud detection scripts (anti-carding) execute heavy JavaScript on every page, even catalog pages
• The INP (Interaction to Next Paint) score is degraded by these scripts blocking the main thread

Our advice: Load these scripts only on pages that need them (forms, checkout) and never on catalog or homepage. The difference can be 2 to 4 seconds in loading time.

Real cases from our tickets

Case #1 — PrestaShop with 94 active modules

Problem: A PrestaShop 1.7 store with a 12-second loading time. The merchant had installed 94 modules, 40 of which were deactivated but still present on the server, and 20 active modules were redundant or unused.

Our intervention: Complete module audit, uninstallation of 35 unnecessary modules, replacement of 8 heavy modules with lighter alternatives, theme optimization. Result: loading time reduced from 12s to 2.8s.

Case #2 — WordPress e-commerce at 18s loading time

Problem: A WooCommerce site on shared hosting with a customized Avada theme, 45 active plugins, and 4 MB product images. PageSpeed mobile score: 8/100.

Our intervention: Migration to a VPS with PHP 8.2 + OPcache + Redis, compression and conversion of 2,400 images to WebP, replacement of 12 plugins with lighter alternatives, properly configured WP Rocket. Result: PageSpeed mobile score from 8 to 72/100, loading time from 18s to 3.1s.

Case #3 — PrestaShop database weighing 8 GB

Problem: A PrestaShop store whose database weighed 8 GB, causing regular timeouts. The logs table alone was 5 GB, expired sessions occupied 1.2 GB, and tables from modules uninstalled 3 years ago were still present.

Our intervention: Cleanup of obsolete tables, purge of old logs, index optimization, MySQL tuning. Result: database reduced from 8 GB to 800 MB, query response time divided by 5.

Case #4 — Catastrophic CLS score due to a slider

Problem: An e-commerce site with an excellent LCP (1.8s) but a CLS of 0.45 — well above the 0.1 threshold. Google penalized the site in mobile results despite a decent loading time.

Our intervention: The culprit: a homepage slider that did not reserve space before loading images, plus ads inserting into content without predefined dimensions. Added explicit dimensions, CSS space reservation, and replaced the slider with a static component. Result: CLS from 0.45 to 0.03.

Case #5 — Anti-bot script doubling loading time

Problem: A PrestaShop merchant who had installed an anti-bot module loading a 380 KB script on every page. The script performed heavy JavaScript calculations to detect bots, blocking the main thread for 2.5 seconds.

Our intervention: Limited the script to form and checkout pages only, async loading with defer, server-side anti-bot solution (fail2ban + .htaccess rules) for other pages. Result: INP from 450ms to 120ms, LCP improved by 2.3 seconds.

PrestaShop optimization: our recommendations

PrestaShop represents the majority of our performance interventions. Here are the specific optimizations we apply:

• Disable native CSS/JS concatenation in PrestaShop (often counterproductive) and use a proper minification tool
• Enable Smarty cache and compile in production mode
• Configure object cache with Redis or Memcached via the dedicated module
• Clean the ps_connections table which grows endlessly (visitor history)
• Optimize hooks — Remove modules from hooks where they are not needed
• Upgrade to PHP 8.1+ — 30% performance gain over PHP 7.4
• Use a CDN for images and static assets
• Audit third-party modules — Some popular modules execute dozens of unnecessary SQL queries

WordPress optimization: our recommendations

WordPress and WooCommerce require a different approach:

• Choose a lightweight theme — GeneratePress, Astra, Kadence rather than overloaded multipurpose themes
• Properly configured cache plugin — WP Rocket, LiteSpeed Cache, or W3 Total Cache (one, not three)
• Disable excessive revisions — Limit to 5 revisions per post
• Native lazy load — WordPress 5.5+ supports it natively, no extra plugin needed
• Disable WordPress embeds and emoji scripts if unused
• Optimize WooCommerce — Disable AJAX fragments on non-shop pages, limit sessions
• Database — Clean expired transients, revisions, orphaned meta

Performance checklist: essential checks

Here are the points we systematically verify during a performance audit:

• PageSpeed Insights score — Target: >70 mobile, >90 desktop
• LCP < 2.5s — The largest visible element must render quickly
• CLS < 0.1 — The page should not "jump" during loading
• INP < 200ms — The site must respond quickly to clicks and interactions
• Total page weight < 3 MB — Including images
• HTTP requests < 50 — Each request has a cost
• TTFB < 600ms — Server response time must be fast
• gzip/brotli compression enabled — For all text files (HTML, CSS, JS)
• Images in WebP/AVIF — With JPEG/PNG fallback for older browsers
• Browser cache configured — Cache-Control headers with appropriate durations
• PHP 8.1+ with OPcache — Check version and configuration
• Optimized database — Clean tables, proper indexes, performant queries

Our performance numbers at a glance

Why trust us with your site optimization?

Since 2018, we have optimized hundreds of e-commerce and showcase sites. Our approach is data-driven, not based on guesswork.

• 900 performance interventions — expertise forged in the field with real cases
• Complete audit — We analyze the server, code, database, assets, and third-party scripts
• Measurable results — Before/after with concrete metrics (PageSpeed, Core Web Vitals, loading time)
• Multi-CMS expertise — PrestaShop, WordPress, WooCommerce, Magento, custom
• Server optimization included — PHP, MySQL, cache, CDN, compression
• Guaranteed SEO impact — Improved Core Web Vitals = better Google ranking