This week in caching: Redis round-trip reduction

This week in caching: Redis round-trip reduction

The cache was fast; the network wasn't. How teams fixed the gap:

— Feed service — replacing 300 sequential GETs with one MGET / pipeline dropped page render from 240ms to 18ms; same Redis, the win was killing 300 network round-trips.
— Laravel app — moving Redis off a remote managed host onto a local unix socket cut per-call latency from 0.8ms to 0.05ms; on a page doing 200 cache calls that's a real 150ms.
— API — Lua scripting a read-modify-write into one atomic call removed a race and a round-trip at once.

The lesson: cache hit latency is dominated by network round-trips, not Redis itself. Batch and co-locate.

Bookmark: redis-cli --latency and --intrinsic-latency — separate network cost from server cost before you tune.