Stop writing caches that no later run restores
Remove cache writes and archives that have no consumer, eliminating work without changing the build result.
How DoorDash used this technique
Read what DoorDash changed and follow the original sources.
Turn off a build cache that CI never restores
Next.js caches Webpack, ESLint and SWC under .next/cache by default, and for large projects the Webpack cache can exceed 5 to 10 GB. CI jobs never saved that cache between runs, so every write was wasted disk activity. Disabling the Webpack disk cache in CI saved three minutes per run.
- Use it when
- A build tool writes a large local cache on every CI run, and no cache step saves or restores that directory.
- Before applying it
- Keep the cache wherever a later run restores it (developer machines, or CI with a cache step whose hit rate you have measured).
Company Playbooks
- Read Anthropic’s playbookRun only affected tests
- Read DoorDash’s playbookRun build and test in parallel, sharded across CI agents
- Read Linear’s playbookBenchmark the same job on faster hardware
- Read Mastra’s playbookStarSling runners for the slowest test workflow
- Read OpenAI’s playbookRank CI fixes by the minutes they save
- Read Ramp’s playbookMove a CPU-bound test suite to a faster CPU
- Read Shopify’s playbookLet an agent iterate against one CI metric
- Read Spotify’s playbookBuild arm64 on native arm64 runners
- Read Stripe’s playbookRun only the tests a change can reach
- Read Uber’s playbookBuild the merge-queue speculations most likely to be needed