playbook/antigravity-awesome-skills/skills/vercel-optimize/references/support-topics/runtime-cache-reusable-data.md

id	title	status	candidateKinds	frameworks	priority	citations	maxBriefChars
runtime-cache-reusable-data	Runtime Cache for reusable server data	active	slow_route external_api_slow	*	84	https://vercel.com/docs/caching/runtime-cache https://vercel.com/docs/functions/functions-api-reference/vercel-functions-package	850

Investigation Brief

Runtime Cache is only useful when the same server-side result is reused across requests. Treat it as a measured alternative when CDN response caching is unsafe or incomplete.

Evidence To Check

Use p75/p95 latency, call count, caller routes, and transfer bytes. In source, identify database queries, external API calls, or expensive computations that return the same result for many viewers.

Do Not Recommend When

Skip per-user data, mutations, secrets, one-off requests, or unknown freshness. Skip Runtime Cache when CDN caching solves the route. For Next with Cache Components, check use cache: remote first; use Runtime Cache only as a justified fallback.

Verification

Name the reusable data, observed route or hostname pressure, required freshness window, and the exact call site to wrap.