A slow store is not just an annoyance. It loses orders quietly, every day, and nothing in your admin tells you it is happening. A tenth of a second faster can lift conversions by around 8 % (the Google/Deloitte study). Here are the usual causes, in the order we normally find them.
1. Images that are far too heavy
The most common culprit by a distance. Product photographs uploaded at full resolution can weigh several megabytes each, and a category page shows twenty of them. The fix: WebP, correct dimensions, and lazy loading so images load as the visitor reaches them rather than all at once.
2. Too many modules
Every module adds something, including when you are not using it. Old, duplicated or badly written modules slow down every page on the store, not only the page they belong to. A regular clear-out is not housekeeping, it is performance work.
3. No caching
Without a cache the server rebuilds every page from scratch on every visit. Turning caching on and configuring it properly is usually the single fastest improvement available — and often the one nobody has done.
4. Slow or general-purpose hosting
PrestaShop on cheap shared hosting is frequently slow for reasons that have nothing to do with the store. A server tuned for PrestaShop makes a difference you can see in the numbers. It is also the fix people resist longest, because the hosting bill is small and visible while the lost orders are large and invisible.
5. A database that has grown wild
Old logs, abandoned carts, stale connection records and search statistics inflate the database over the years. Cleaning and optimising it speeds up queries across the whole store.
How we go about it
Measure first — PageSpeed, real load time, where the bottlenecks actually are — then optimise, then show the improvement with before and after numbers. Guessing at performance is how people spend a month making a store 4 % faster.
Is your store slow? Order a store audit and you get it in writing within two working days, or look at the pricing first.