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Lightning CMP

Performance & Core Web Vitals

Lightning CMP is built so the banner costs you nothing measurable in Core Web Vitals — a 100/100 Lighthouse score with the banner running is the design target, not a best case.

Why it’s fast

Section titled “Why it’s fast”
  • ~12 KB gzipped, loaded async — never render-blocking.
  • Shadow-DOM UI — the banner’s styles are fully isolated, so there’s no layout thrash against your page CSS.
  • Off-critical-path loaders — bridges inject vendor scripts at idle time, after first paint.
  • Edge-resolved config — one round-trip to a warmed connection (preconnect), not a chain of blocking requests.

Keep it fast

Section titled “Keep it fast”
  • Keep the preconnect in the snippet.
  • Don’t move the CMP <script> out of async, and don’t let a defer-all optimiser touch it (that hurts both correctness and timing — see Troubleshooting).
  • Prefer bridging Google over hard-blocking it — the bridge loads off the critical path with correct ordering.