The tools that give you the full picture
Google PageSpeed Insights is the standard starting point and ties directly to the metrics Google uses for ranking. GTmetrix gives a more detailed waterfall of exactly what's loading and when. WebPageTest lets you simulate different locations and connection speeds — useful if you have customers outside major cities on slower connections.
Test both mobile and desktop separately
These scores are often very different. A site that feels fast on a office desktop with fibre internet can be sluggish on a mobile connection in regional Australia. Always check both, and weight mobile more heavily since that's where most traffic now comes from.
What to actually look for in the results
Don't just look at the overall score — look at the specific opportunities listed: unoptimised images, render-blocking resources, excessive JavaScript, and server response time. These are the levers you can actually pull.
Server response time is often overlooked
If your Time to First Byte is slow, no amount of front-end optimisation will fully compensate. This usually points to hosting quality, database queries, or lack of caching. Budget shared hosting is the most common cause on small business sites.
Set a benchmark and re-test after changes
Speed testing isn't a one-off task. Test before and after any theme change, plugin install, or redesign — it's very easy for a new feature to quietly undo months of optimisation work without anyone noticing until traffic drops.
Key Takeaways
- Use PageSpeed Insights, GTmetrix, or WebPageTest for a full picture
- Always test mobile and desktop separately
- Focus on the specific opportunities listed, not just the overall score
- Server response time often needs a hosting fix, not a code fix
- Re-test after every significant site change