My site slowed down overnight
A site that suddenly takes eight seconds to open when it took two last week has not simply aged. Something changed, on a specific date, and finding that date is half the diagnosis. A slowdown that has always been there and one that appeared yesterday are not treated the same way at all.
Describing the slowdown precisely
- The browser sits on a blank page for several seconds before anything appears: the server is slow to answer.
- The page appears quickly but stays unusable, images arriving one by one: the problem is in what the page loads, not in the server.
- Only the admin area is slow; the shop your customers see behaves normally.
- The slowdown returns at a fixed hour, or only during your campaigns.
Two very different slowdowns
The first figure to isolate is how long the server takes to send the first byte of the page, known as TTFB. As long as that stays within a few hundred milliseconds, the server is doing its job: the perceived slowness then comes from page weight, uncompressed images and third-party tracking or chat scripts. Those are two separate projects, with two separate budgets.
If the first byte instead takes several seconds, the problem sits upstream of rendering: too many or too heavy database queries, a disabled cache, an old PHP version, or a saturated server. On shared hosting, saturation can even come from another site sharing the same machine.
Finding what changed
-
Date the start
Ask your team and check your analytics: the exact date of the switch guides everything else. One day, not one week.
-
List that week’s changes
A CMS, module or plugin update, a new advertising script, a theme change, a bulk product import, a change of hosting plan.
-
Compare a simple page with a heavy one
If the legal notice page is as slow as a category page, the cause is global. If only the category page suffers, it lies in the catalogue or the filters.
-
Test outside peak hours
A slowdown that vanishes at night points to a resource limit, not a code defect.
-
Look at table sizes
Connection logs, statistics, abandoned carts and stored searches grow without limit and eventually slow every query.
Carry on with the right page
-
Diagnosing a slow shop
The full measurement method, before deciding what to optimise.
-
Slow PrestaShop shop
If the cause sits in PrestaShop: cache, CCC, category queries.
-
Slow WordPress or WooCommerce site
If the cause sits in WordPress: plugins, product queries, admin area.
-
TTFB explained
The figure that separates a server slowdown from a rendering slowdown.
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.