In the tense moments of an early-morning deployment, an 8-minute build means 8 minutes of anxiety. If "npm install, 4 minutes" accounts for half of those 8 minutes, those 4 minutes are waste spent re-downloading the same packages from the internet every time. In theory, a cache could cut that to 40 seconds. But in practice CodeBuild's cache behaves completely differently depending on "where it's stored," and there's a paradox where a misconfigured cache actually makes things slower.
Optimizing CodeBuild's build time consists of five layers: (1) compute resource selection, (2) cache strategy, (3) source clone optimization, (4) Docker layer cache, and (5) Build Batch parallelization