I have no idea if this is particular to our app (standard Next.js with pnpm and eve), but the build cache provided almost no benefit (cache preparation and uploads accounted for ~70% of our build time) and non-trivially increased build costs.

Disabling it didn't noticeably change our to ready time.

People might want to consider disabling the cache and see how it effects their builds:

1VERCEL_FORCE_NO_BUILD_CACHE=12VERCEL_FORCE_NO_BUILD_CACHE_UPLOAD=1

Also the agent is pretty good at analyzing these logs, so it's easy to just ask it how much time it's spending on build caching.