PageSpeed Monitoring
Most websites get their speed checked exactly once: at go-live, or when someone complains. In between lies a lot of time in which values can tip unnoticed. Monitoring PageSpeed automatically closes this gap before it costs rankings.
Why good PageSpeed values don't last
A website is a moving system. A plugin update brings new JavaScript, the editorial team uploads an uncompressed hero image, a third-party script gets sluggish, the host changes something in the server configuration. Every single one of these small things can worsen LCP or CLS, and none of them announces itself.
The insidious part: the regression usually only gets noticed once its consequences become visible. Rankings slip, enquiries dwindle, and the root-cause hunt begins weeks after the actual trigger. By then nobody remembers which update or which piece of content set it off.
Why manual checking isn't enough
PageSpeed Insights and Search Console are good tools, but as monitoring both fall short:
- PageSpeed Insights only measures when someone remembers: one snapshot per manual call. What happens between two checks stays invisible
- Search Console reacts sluggishly: its Core Web Vitals data is based on 28-day field data. By the time a regression shows up there, it's almost a month old
- Nobody checks all the pages: manually, it's almost always just the homepage that gets tested, while landing pages and shop pages go unwatched
- No alerts: neither tool speaks up on its own. Whoever doesn't actively check learns nothing
Automatic monitoring inverts the principle: the measurement runs at fixed intervals in the background, and a report comes exactly when a value breaches a defined threshold. No more, no less.
What good PageSpeed monitoring must deliver
- Regular, automatic measurements: at intervals matching the website's rate of change, from a few hours to daily
- Mobile and desktop separately: Google evaluates mobile first, but many problems only appear in one of the two variants
- The relevant metrics: Core Web Vitals like LCP and CLS plus the four PageSpeed categories performance, SEO, accessibility and best practices, ideally from the same data source Google itself uses
- Thresholds instead of noise: an alert only when a value genuinely falls below the defined limit, ideally configurable per metric and separately for mobile and desktop
- History instead of snapshots: a chart across weeks shows when a value tipped and makes the trigger narrowable
Our answer to it, free of charge
Because we found no tool on the market doing exactly that in an uncomplicated way, we developed it ourselves and provide it free of charge:
Our own tool · free
SiteSentry — monitor PageSpeed automatically
Enter a URL, set thresholds, done: SiteSentry measures your pages automatically via the official Google PageSpeed API, at intervals from two hours to daily, mobile and desktop. You set the thresholds individually per metric and type; if one is breached, an email arrives immediately. The history shows when and through what something changed.
More on SiteSentryFor our maintenance clients, the monitoring is the trigger to act: if a value spikes, we look at the history, find the cause and fix it, often before the regression even reaches Google's 28-day field data. How we go about it technically is described on the PageSpeed optimisation page.
Related topics
PageSpeed & Core Web Vitals
Monitoring detects the problem; optimisation fixes it. More on PageSpeed optimisation.
SEO audit
The entry point when you don't yet know where your website stands at all. More on the SEO audit.
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