Case: Cached sitemap generation cut TTFB 4.2s → 180ms

Case: Cached sitemap generation cut TTFB 4.2s → 180ms
A dynamic sitemap rebuilt from a live query on every Googlebot fetch. Slow responses caused fetch timeouts.
What we did:
— Generated files to static storage on a 6-hour cron
— Served them as flat files, not through the app
— Set a hard rebuild after any bulk publish event
Measured outcome over 3 weeks:
— Sitemap TTFB: 4.2s → 180ms
— 'Couldn't fetch' sitemap errors in GSC: 14/week → 0
Checklist:
✅ Sitemap served as a static file or fully cached
✅ Response under 1s at p95
✅ Rebuild triggered on bulk content changes
Definition of done: Googlebot fetch returns 200 in under 1s with no timeout errors for 14 consecutive days.