Portfólio
Aug 19, 2026
The CDN cache fighting the ISR — and holding the TTFB at 3.6s
A wrong Cache-Control header in vercel.json was overriding the revalidate=1800 ISR setting and turning every cache expiry into two synchronous GitHub calls inside the TTFB. The story of how cold cache became warm: 3.6s down to 140ms.
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