A performance audit for every release
This page is for designers maintaining a theme. Performance degrades release by release unless measured. How to build a fast theme is in Theme performance and Measuring CLS and LCP.
What to measure
| Measure | How | Watch for |
|---|---|---|
| Page weight | Browser developer tools, network panel | Growth without a reason |
| Requests | The same | New fonts, scripts, images |
| Image sizes | The same | Images larger than displayed |
| Layout shift (CLS) | A lab tool such as Lighthouse | Images without dimensions, late fonts |
| Largest contentful paint (LCP) | The same | Big hero images, render-blocking files |
Measure on the test installation with the packer active, so stylesheets and scripts are bundled as on a live site.
Step by step
- Measure the front page, an article and a list with the previous release; write the numbers down.
- Update and measure the same pages the same way.
- Compare. Explain or fix every increase.
- Note notable improvements in the changelog.
Related pages
- Image performance
- Benchmarking
- Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.
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