Lighthouse says 86. Run it again: 91. Building a free local console for scores you can defend
You know this loop. A page feels slow. You open the Lighthouse panel in DevTools, hit Analyze, and get 86 . You change nothing, run it again, and get 91 . You run it a third time out of spite: 78 . Now which number goes in the PR description? This isn't a bug. Total Blocking Time is CPU-sensitive and worth roughly 30% of the Performance score, so anything else your laptop is doing — a Slack…
Lighthouse often reports a low performance score, such as 86, after quickly running it once. However, after multiple attempts, the score might improve to 91, which is still not ideal. The issue is that Total Blocking Time (TBT), a crucial factor in performance scoring, is sensitive to the CPU load at the time of the test. Other background processes on your laptop, like notifications or indexing, can affect the TBT number.
Lighthouse Performance scores can vary by around ±5 points on repeated runs, making a single result unreliable. Additionally, PageSpeed Insights (PSI) requires a public URL, making it impossible to audit a local page running on your machine. LightAudit Score is a free, locally-run console that addresses these issues. It runs Lighthouse on your own machine, repeats the test enough times to provide meaningful results, and stores the results locally. This way, you can compare your page's performance over time and identify areas for improvement.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
