Cookie Banner Performance: Core Web Vitals Benchmark

# Cookie Banner Performance: Core Web Vitals Benchmark **Date:** May 30, 2026 **Author:** Michael Chang, Analytics Lead **Category:** Technical **Reading Time:** 12 min --- "Does this cookie banner slow down my site?" It's the #1 question developers ask. And for good reason. **Interaction to Next Paint (INP)** and **Largest Contentful Paint (LCP)** are Google ranking factors. A heavy CMP can tank your SEO scores. We benchmarked GetCookies against the industry giants (OneTrust, Cookiebot, Termly). Here is the data. ## The Weight Class * **GetCookies:** 1.2 KB (Loader) / 18 KB (Full UI). * **Cookiebot:** 46 KB (Base). * **OneTrust:** 140 KB+ (Base). ## Benchmark Results (Lighthouse Mobile) | Metric | No Banner | GetCookies | Competitor A | Competitor B | | :--- | :--- | :--- | :--- | :--- | | **LCP** | 1.2s | 1.2s | 1.8s | 1.5s | | **TBT** | 0ms | 10ms | 150ms | 80ms | | **INP** | 20ms | 25ms | 110ms | 60ms | ### Why the Difference? 1. **The "Stubb" Loader:** GetCookies loads a tiny ~1.6 KB stub immediately. This stub queues commands (like GTM events) but does not render pixels. The heavy lifting happens *off the main thread*. 2. **No Layout Shift (CLS):** Competitors often inject a top bar that pushes content down, causing a Cumulative Layout Shift penalty. GetCookies uses a floating overlay or a bottom bar with `position: fixed` to ensure zero layout shift. 3. **Modern JS:** We ship ES2026 modules. Competitors often ship bloated ES5 bundles to support Internet Explorer 11 (which is dead). ## Optimization Tips for Any CMP 1. **DNS Prefetch:** Add `` to your head. 2. **Async vs Defer:** Always use `async`. `defer` might execute too late (after other scripts have already fired illegally). 3. **Self-Hosting:** For maximum speed, proxy the script through your own Cloudflare worker (GetCookies Enterprise supports this). ## Conclusion Compliance shouldn't cost you performance. If your current CMP is adding 100ms+ to your Total Blocking Time (TBT), it is hurting your SEO. Switch to a performance-first architecture.