Myth: more cache layers always means faster

Myth: more cache layers always means faster
This week in caching, the layering fallacy:
— The claim: stack page cache + object cache + CDN + browser cache and speed compounds.
— The correction: each layer adds an invalidation surface; a stale object cache can poison your fresh page cache, so a miss now costs a multi-layer rebuild instead of one.
— Worth your time: audit which layer actually owns the TTL for a given URL before adding another. Two coherent layers beat four that fight over the same key.
Bookmark: map your stack as a dependency tree, not a pile. The bottom layer's staleness window caps everything above it.