You can only improve what you measure. A few free tools will run the diagnosis for you.
The go-to tools
- PageSpeed Insights (Google): scores your site and lists what to fix.
- GTmetrix: detailed analysis of the loading process.
- WebPageTest: advanced testing with a full request waterfall.
What to look at
Beyond the overall score, keep an eye on loading time, total page weight and the number of requests. The “Core Web Vitals” (LCP, CLS and so on) are the metrics Google tracks.
Method: measure BEFORE any optimisation, write the numbers down, then measure again after each change.