Per-key bookkeeping quietly becomes the product at scale.

Per-key bookkeeping quietly becomes the product at scale. Cloudflare cut ~100 TB by rethinking per-entry layout in 1.1.1.1’s DNS cache, and the lesson is broader: caches, dedupe stores, session maps, vector-serving layers, and webhook buffers all pay when you store one extra field per key. You should audit what you can derive instead of persist, and treat memory shape as a reliability decision rather than a cost tweak. Small layout changes—drop redundant owners, pack variants, or store compact wire blobs—are cheap to prototype and can avoid capacity and latency failures later.