Performance Scores
Every report and page in PerfLeaf is assigned a performance score and a grade to give you a quick, at-a-glance health indicator.
Score and grade
Section titled “Score and grade”- Score — a number from 0 to 4 (higher is better).
- Grade — a letter from A to D derived from the score:
| Score | Grade | Meaning |
|---|---|---|
| 3.5 – 4.0 | A | Excellent |
| 2.5 – 3.4 | B | Good |
| 1.5 – 2.4 | C | Needs improvement |
| 0 – 1.4 | D | Poor |
Six metric categories
Section titled “Six metric categories”The overall score is a weighted average of six categories. Each category is independently scored and graded:
Core Web Vitals
Section titled “Core Web Vitals”Based on LCP, CLS, INP, FCP, and TTFB thresholds. Failing more CWVs lowers this category score significantly.
Page Assets
Section titled “Page Assets”Evaluates total payload size and individual resource sizes (JS, CSS, images). Large bundles reduce this score.
Accessibility
Section titled “Accessibility”Based on the number of automated WCAG violations found. Zero violations = A grade.
Security
Section titled “Security”Checks for HTTPS, CSP, HSTS, X-Frame-Options, X-Content-Type-Options, and Referrer-Policy headers.
DOM Stats
Section titled “DOM Stats”Measures DOM complexity: node count, tree depth, inline style count, and excessive tag usage.
Estimates the carbon emissions per page load. Heavier pages produce more CO₂.
Site vs page scores
Section titled “Site vs page scores”- Page score — calculated from that page’s individual metrics.
- Report score — the average of all page scores in the report. Category grades show the most common grade across pages (with the worst grade as tiebreaker for ties).
Using scores to prioritise
Section titled “Using scores to prioritise”Focus on categories with a C or D grade first — the AI recommendations system also uses your grades to prioritise its suggestions.