Curated comparison
Hydration mismatch vs stable SSR first paint
Side-by-side: nondeterministic client trees versus a stable server render that hydrates cleanly.
The comparison
| Pattern | First paint | Interactivity | SEO / AEO |
| --- | --- | --- | --- |
| `Date.now()` / `window` branches in render | Flicker / warning | Handlers may miss | Unstable text for crawlers |
| Stable SSR + `useEffect` enhance | Matches HTML | Reliable after hydrate | Consistent citations |
Takeaway
Hydration failures are conversion leaks wearing a performance costume. Guides: [Next.js hydration](/guides/nextjs/hydration), [React hydration](/guides/react/hydration).
Try it
Compare two public URLs on [/labs/compare](/labs/compare) or publish an Open Audit after a sandbox run.