Setting the file. One moment.
Subchapter 7.29
references/support-topics/external-api-critical-path-platform.mdMarkdown1 KBView on GitHub
External API candidates are actionable only when the slow hostname is on a customer route’s critical path. Prove the route waits on it before suggesting a cache, payload, or post-response change.
Use hostname latency, caller routes, transfer bytes, and source awaits. Check sequential calls, overbroad payloads, repeated shared data, and side effects that can move after the response.
Do not cache mutations, secrets, per-user responses, or unknown freshness contracts. Do not blame Vercel runtime when the upstream owns the latency.
Name the hostname, caller route, observed p75/p95 or bytes, and exact await or fetch line that blocks the response.