Accurate performance testing requires controlling variables and using multiple, complementary tools.
Begin with a baseline: measure your site before changes using Lighthouse (in Chrome DevTools), PageSpeed
Insights, and WebPageTest. Each tool offers different perspectives—field data, lab data, and granular
waterfall timing. Test multiple times and average results to account for variability. When running local
Lighthouse, throttle the network and CPU to simulate mid‑range mobile devices, which better reflects
real‑world conditions.
After enabling features in WP Lightning Load, repeat tests under the same conditions and compare key
metrics: FCP, LCP, CLS, TBT/INP, and request/byte counts. Use the Network panel to confirm that minified
and cached assets are served as expected. Run a cache‑warm pass and a cold pass to assess both
first‑time and repeat visit performance. If you use a CDN, consider testing from multiple locations in
WebPageTest to capture edge‑caching effects.
Finally, monitor real user metrics (RUM) via tools like Google Analytics 4 or dedicated RUM platforms to
validate improvements for your actual audience. Lab scores are valuable for diagnosis, but real‑world
data confirms that optimizations translate into better experiences and engagement.