How to Batch Small CI Jobs to Cut Startup Overhead

Ten tiny jobs each pay the same checkout and setup cost; one batched job pays it once.

Every job re-checks-out the repo and re-installs tooling before doing seconds of real work. When many jobs are that small, the fixed setup overhead dominates. Batching related work into fewer jobs amortizes it.

Steps

• Find jobs whose real work is short relative to their setup.
• Merge related short jobs into one job with sequential steps.
• Keep genuinely parallel, long jobs separate so total wall time does not grow.

Workflow

jobs:
  checks:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm
      - run: npm ci
      - run: npm run lint
      - run: npm run typecheck
      - run: npm run test:unit

Tradeoffs

• Batching serializes work, so it can add wall-clock time versus parallel jobs.
• Batch only where setup dominates; keep long independent jobs parallel.

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