Product Search · SSR vs RSC · Mobile
Desktop reports use 50 ms artificial DB delay to emulate real-world load
This demo app is small and fast — under normal conditions all three rendering strategies score similarly on desktop.
PageSpeed Insights does not throttle CPU or network on desktop, so it cannot surface the performance differences
that matter in production. Adding ?delay=50 to every
page injects a 50 ms sleep after each database query, simulating the heavier queries and higher latency of a real-world application.
This makes the RSC streaming advantage clearly visible in Lighthouse scores. The 50 ms delay emulates typical database latency
and API response times seen in production applications under load.
| Metric | SSR | RSC | Δ |
|---|---|---|---|
| Performance score | 98 | 99 | +1% |
| First Contentful Paint | 1.27 s | 1.4 s | +10% |
| Largest Contentful Paint | 1.81 s | 2.02 s | +12% |
| Total Blocking Time ★ | 118 ms | 9 ms | -92% |
| Cumulative Layout Shift | 0.0 | 0.0 | +0% |
| Speed Index | 2.33 s | 2.65 s | +14% |
| Script Bootup | 429 ms | 193 ms | -55% |
| Total Transfer | 553 KB | 254 KB | -54% |
★ Blocking Time has the biggest impact on Google's performance score (30%) — it measures how long users wait before they can tap, scroll, or type (LCP 25%, CLS 25%, FCP 10%, SI 10%).
product-search_ssr-mobile
product-search_rsc-mobile