Performance and Core Web Vitals

The Performance tab surveys every crawled page for client-side rendering behaviour and Core Web Vitals, flags pages that need attention, and summarises the findings in a single view. It requires headless mode (renderJavascript: true) — without it, the crawler does not execute page scripts and cannot collect runtime metrics.

Stats

Four summary figures appear at the top of the tab:

Stat	What it reports
Pages analyzed	Total number of pages where performance data was collected during the crawl.
Average Consuela performance score	The mean score across all analyzed pages. This is Consuela's own performance score, not a Lighthouse score — the two measure overlapping signals but will not produce the same number. See the score disclaimer below.
Poor score count	Number of pages whose Consuela performance score falls below the acceptable threshold.
Client-side rendered count	Number of pages that relied on JavaScript to render their primary content — a signal that server-side rendering is absent or incomplete.

Core Web Vitals

Below the summary stats, the tab shows average Core Web Vitals across the entire crawl:

Metric	What it measures
LCP (Largest Contentful Paint)	Time until the largest visible content element finishes rendering, in milliseconds.
FCP (First Contentful Paint)	Time until the first piece of content — text, image, or canvas — appears on screen, in milliseconds.
CLS (Cumulative Layout Shift)	A unitless score representing the total unexpected movement of visible elements during page load.
Console issue count	Total number of warnings and errors logged to the browser console across all analyzed pages.

Poor-performing pages

Pages whose metrics exceed acceptable thresholds are listed in a table for individual inspection. Each row contains:

Column	Description
URL	The page address. Click to open it in the detail view.
Consuela score	The page-level performance score assigned by Consuela.
LCP	Largest Contentful Paint, in milliseconds.
FCP	First Contentful Paint, in milliseconds.
CLS	Cumulative Layout Shift score.
TBT	Total Blocking Time — the sum of all long-task durations above 50 ms, in milliseconds.

Thresholds

Each metric is colour-coded against the thresholds below. Green means the value is in good order, yellow signals that it needs attention, and red marks a poor result.

Metric	Green (good)	Yellow (needs attention)	Red (poor)
LCP	< 2500 ms	2500 – 4000 ms	> 4000 ms
FCP	< 1800 ms	1800 – 3000 ms	> 3000 ms
CLS	< 0.1	0.1 – 0.25	> 0.25
TBT	< 200 ms	200 – 600 ms	> 600 ms

These ranges align with the Web Vitals initiative thresholds published by Google. The colour appears beside the metric value in both the summary averages and the individual page table, so pages that exceed a threshold are visible at a glance.

Score disclaimer

The performance score shown in this tab is Consuela's own measurement. It is not a Lighthouse score. Consuela and Lighthouse measure overlapping signals — Core Web Vitals, render timing, blocking time — but they weight them differently, collect them under different conditions, and will not produce the same number for the same page.

If you run Lighthouse independently on the same URL, expect the two scores to diverge. Neither is wrong; they are different instruments applied to the same subject. When reporting performance findings, note which tool produced the number so readers are not left comparing figures from two different scales.