Diagnose a slow site

Separate a slow server from a slow page, then find the plugin or query responsible.

"The site is slow" covers several different problems. Find out which one you have before changing anything.

Is it the server or the page?

curl -o /dev/null -s -w "dns:%{time_namelookup} connect:%{time_connect} ttfb:%{time_starttransfer} total:%{time_total}\n" https://example.com

• TTFB under 200 ms — the server is fine. The slowness is in the browser: images, fonts, scripts.
• TTFB above 800 ms on a cached page — something is bypassing the cache. Check for a session cookie set on every request.
• TTFB above 800 ms while logged in only — normal to a point: admin requests always run PHP. Investigate if it exceeds two seconds.

Find the cause

1. Read the slow query log

   Sites → Logs → Slow queries. Repeated queries over a second usually point to one plugin.

2. Profile the plugins

   Query Monitor on staging shows time spent per plugin and per query. Never leave it active on live.

3. Check the size of the page

   An uncompressed hero image can be heavier than everything else combined.

4. Check external calls

   A slow third-party API called on every page load makes your site as slow as theirs. Cache the response.