Why is my PrestaShop site slow?

Across 30 PrestaShop audits run in 2025-2026, the main causes by frequency are: (1) too many active and outdated modules, especially cross-selling and tracking modules that call external APIs and block rendering; (2) unindexed SQL queries on ps_product_attribute or ps_specific_price as the catalogue grows; (3) misconfigured or absent PrestaShop cache (Smarty + CCC); (4) images served as JPEG/PNG without WebP variants or lazy-loading; (5) shared hosting under-sized for traffic; (6) no Redis or Memcached for sessions and object cache; (7) blocking chat/tracking JS; (8) unoptimised custom theme (unminified CSS/JS, Google fonts loaded without preload). A single one of these can cost 2 seconds; stacking them can triple load time.

What speed gain can I expect?

Real cases across the last 12 audits: median LCP from 4.2s to 1.6s (-62%), median INP from 380ms to 180ms (-53%), TTFB from 1.4s to 0.4s (-71%). These gains come from 3 to 5 main levers and 30 days of work. No magic promises: if your hosting caps out, we will tell you and quote the migration. No vanity 'green Pagespeed audit' that turns out to be useless in real production — we optimise on real traffic with Real User Monitoring.

Does a performance audit impact SEO?

Yes, positively and directly. Since Core Web Vitals (LCP, INP, CLS) were integrated into Google ranking in 2021-2024, an e-commerce store with LCP > 2.5s loses positions on commercial queries. On one of our clients (cosmetics store), bringing LCP from 3.8s down to 1.4s gained 22% organic traffic in 60 days (GSC data). Beyond SEO, your conversion rate is the biggest beneficiary: every extra second of load time loses on average 7% conversion on mobile (Akamai 2024).

Do I need to change host to speed up PrestaShop?

Not always. Across audited sites, 60% of gains come from code and configuration, 40% from hosting. If your TTFB (Time To First Byte) exceeds 800ms at peak hours on a store > 1000 products, yes, you probably need to migrate to VPS or dedicated. For stores < 500 products with TTFB < 400ms, code and cache optimisation is enough. KLN-WEB never pushes a migration without a reason: we show you the numbers before any recommendation.

How long before I see the first results?

'Technical' optimisations (CCC activation, Redis setup, WebP conversion, minification, lazy-loading images) deliver immediate results — measurable in Lighthouse at deployment. SEO gain (Core Web Vitals in Search Console) is measured on a rolling 28-day window by design. For traffic and conversion, we typically see the first effects between D+14 and D+45 after going live. RUM (Real User Monitoring) tracking is included in the pack to measure the real gain on your visitors.

Free audit · Measurable gain in 30 days

Is your PrestaShop slow?
we speed it up for real.

LCP > 3s, sluggish cart, product page taking 5s to load: you know you are losing sales, and you know it is fixable. Across the last 12 optimisations, median gain −62% on LCP and +22% organic traffic in 60 days.

Or call directly: +33 6 78 85 05 63

✓ Free 30-min pre-audit ✓ Firm quote within 24 business hours ✓ From €60/h excl. VAT · Measurable RUM gain

📊 Real results

Before / after on 3 optimised stores

GSC + Lighthouse + RUM measurements, 60-day rolling window. Not promises, numbers.

Store	LCP before	LCP after	INP before	INP after	Business impact
Ethical fashion PS 8.0, 1,200 SKU	4.2s	1.6s	420ms	170ms	+22% organic traffic over 60 days (GSC)
Wines & spirits PS 1.7.8, 380 SKU	3.7s	1.4s	310ms	140ms	Mobile conv. rate +18%, AOV stable
Organic cosmetics PS 8.1, 2,800 SKU	5.1s	2.0s	480ms	210ms	−34% bounce rate on product pages
Median across 12 optimisations	4.2s	1.6s	380ms	180ms	−62% LCP · −53% INP

⚙️ Concrete levers

The 8 levers we pull

Always in this order, from most immediate to most structural. Each has a measurable, quantified impact in the audit.

01 PrestaShop cache enabled and properly configured

CCC (Combine, Compress, Cache) in production mode, Smarty cache in compile_check=off, browser cache via Cache-Control: public, max-age=31536000 headers on versioned assets. Typical impact: −800ms to −1.2s on LCP.

02 WebP images + native lazy-loading

Automatic JPEG/PNG → WebP conversion with fallback, loading="lazy" on every off-viewport image, explicit width/height attributes to prevent layout shift. Impact: −1.5s to −2s on LCP, CLS close to 0.

03 Audit and disable useless modules

Review of every active module, identification of duplicate tracking modules (Google, Meta, TikTok), orphan modules never used, chat modules loading 800KB of JS. Clean disable via admin + SQL cleanup of orphan hooks. Impact: −150 to −400ms on TTFB.

04 DB indexing of critical queries

Slow query profiling via EXPLAIN and slow_query_log. Adding indexes on ps_product_attribute (id_product, default_on), ps_specific_price (id_product, id_country, from, to), ps_orders (id_customer, date_add). Impact: TTFB cut by 2 to 4× on catalogues > 1000 products.

05 Redis or Memcached object cache

On PrestaShop 8.x/9.x, activation of Redis object cache (sessions + app cache). On 1.7.x, configuration via defines_custom.inc.php. Impact: −250ms to −500ms on TTFB, essential at peak hours.

06 Deferred / async non-blocking JS

Audit of JS injected by modules: tracking scripts set to defer, chat widgets in delayed load after user interaction, duplicate removal (gtag.js loaded 3 times by 3 different modules is classic). INP impact: −150 to −200ms.

07 Self-hosted, preloaded fonts

Migration of Google Fonts to self-hosting (GDPR-friendly too), <link rel="preload"> on WOFF2 files used above the fold, font-display: swap. Impact: −300ms on FCP, FOIT eliminated.

08 Hosting migration if hitting the ceiling

If TTFB stays > 800ms at peak hours after the 7 previous levers, hosting is the bottleneck. Assisted migration to optimised VPS (Kinsta, WP Engine, SiteGround, Hetzner) or PrestaShop-specialised hosting. Impact: TTFB down to 150-300ms.

🩺 Our audit

What we look at, in this order

Full audit in 4h. Deliverable: PDF report with quantified recommendations and prioritised action plan.

Step 1

Baseline measurement Lighthouse + WebPageTest from 3 regions, RUM via Cloudflare Web Analytics on a rolling 14-day window. We start from real numbers, not lab Lighthouse.

Step 2

Server profiling Reading php-fpm.log, Xdebug or Tideways profiling on 3 key pages (home, category, product). Identify time spent in PHP vs SQL vs network.

Step 3

Database audit Slow query log enabled for 24h, analysis of queries > 100ms. EXPLAIN on the top 20. Index recommendations specific to your catalogue.

Step 4

Module audit List of active modules, version, last vendor update, JS/CSS payload size injected, hooks attached, estimated performance impact. Recommendation: keep, update, replace, remove.

Step 5

Hosting audit Hosting type, PHP version, OPCache configured, memory_limit, Redis/Memcached presence, HTTP/2, Brotli. If limitations detected: before/after migration comparison.

Deliverable

PDF report + quantified roadmap 30-40 pages. For each lever: estimated impact in seconds/ms, implementation time, cost. You decide what to enable.

💰 Pricing

Pricing stated up-front

Free pre-audit. For the optimisation, you know exactly what it costs before we touch the code.

🔍 Pre-audit

Pre-audit

measure the real speed

0€free

30 min · no commitment

Lighthouse + RUM measurement (LCP, INP, CLS)
Top 3 levers for your case
Firm quote with estimated gain in ms
You decide if we continue

Start the pre-audit →

⚡ Most requested 🔧 Optimisation

Targeted optimisation

speed it up for real

from 60€excl. VAT

per diagnostic · price stated up-front

Lighthouse + RUM measurement before optimisation
Lever activation (cache, WebP, JS, DB, Redis...)
After measurement + quantified comparison
Written report real gain in seconds
30-day RUM tracking after going live

🛡️ Maintenance

Performance maintenance

optimisation spread monthly

from 50€/ month

24/7 monitoring · no commitment

2h of dev/month rollable (Performance plan)
Daily backups externalised
Monthly Core Web Vitals tracking
Progressive optimisations no big cheque

❓ FAQ

PrestaShop performance — frequently asked questions

Across 30 audits in 2025-2026, by frequency: (1) too many active and outdated modules (cross-selling, tracking, blocking external APIs), (2) unindexed SQL queries on ps_product_attribute or ps_specific_price as the catalogue grows, (3) misconfigured Smarty + CCC cache, (4) JPEG/PNG images without WebP or lazy-loading, (5) under-sized shared hosting, (6) no Redis/Memcached, (7) blocking chat/tracking JS, (8) unoptimised custom theme. A single point can cost 2s; stacking them can triple load time.

Free pre-audit (30 min), then optimisation on quote, from €60/h excl. VAT. Firm quote sent within 24 business hours before any work starts. Quick optimisations (cache, WebP, JS, fonts) take 4-8 hours; deep work (module rewrite, DB, host migration) is quoted after the audit. Included in Performance maintenance at 2h/month rollable.

Real cases across 12 optimisations: median LCP 4.2s → 1.6s (−62%), median INP 380ms → 180ms (−53%), TTFB 1.4s → 0.4s (−71%). Gains delivered with 3 to 5 main levers across 30 days. No magic promises: if your hosting caps out, we tell you and quote the migration.

Yes, positively. Since Core Web Vitals were integrated into Google ranking (2021-2024), LCP > 2.5s loses positions on commercial queries. Client case: LCP 3.8s → 1.4s = +22% organic traffic in 60 days (GSC). Above all, every extra second loses 7% conversion on mobile (Akamai 2024).

Not always. 60% of gains come from code and configuration, 40% from hosting. If TTFB > 800ms at peak hours with catalogue > 1000 products, yes you should migrate (VPS or dedicated). For stores < 500 products with TTFB < 400ms, code optimisation is enough. We never push a migration without a reason.

Technical optimisations (CCC, Redis, WebP, minification, lazy-loading) deliver immediate results (Lighthouse at deploy). SEO gain is measured on a rolling 28-day window. For traffic and conversion, first effects typically between D+14 and D+45 after going live. RUM tracking included to measure the real gain on your visitors.

15 min to see where you stand

Free 30-min pre-audit: LCP, INP, CLS, the top 3 levers for you. No commitment, no fluff.

📞 +33 6 78 85 05 63

Is your PrestaShop slow?we speed it up for real.

PrestaShop performance audit and optimisation