Vital Signs

About

A live performance overlay on every page.

━━━ What you see ━━━

A panel at the bottom right that updates once per second and shows:

  • TTFB, FCP, LCP, CLS — the Core Web Vitals that decide how Google ranks
    your page and how users feel about it
  • Long Tasks — how often the main thread has been blocked for more than 50ms
  • Resources — total request count and transfer size
  • DOM Nodes — flags pages getting too heavy for the renderer
  • JS Heap — current memory footprint

Auto-detects .aspx pages and shows three extra metrics:

  • ViewState size — catch ViewState bloat that slows down postbacks
  • .axd request count — spot ScriptResource/WebResource overuse
  • Miscellaneous hidden fields — the other silent contributor to page weight

Every metric is shown with green/amber/red thresholds drawn from web.dev and Lighthouse guidance, so you don't have to remember what "good" looks like.

━━━ Layout visualizer ━━━

Click "Show Boxes" next to DOM Nodes to outline the page's semantic regions — header, nav, main, aside, footer, hero, UpdatePanels, active tab panes — each labeled with its node count.

━━━ Per-site control ━━━

  • Toggle the overlay on or off per hostname
  • Pick exactly which metrics appear
  • Click any metric label to see its reference documentation

━━━ Privacy ━━━

We don't care about your data so we don't collect, transmit, sell, or share it. Every measurement is computed locally in your browser and shown only to you. No analytics, no telemetry, no remote code, no third-party SDKs, no network requests of any kind. 

Permissions:
  • storage — remembers your per-site on/off toggle and metric preferences.
  • activeTab — lets the popup identify the hostname of the current tab.
  • Host access (<all_urls>) — required because performance metrics must be
    measured on whichever page you're viewing.