Speed Up & Optimize CI

Make pipelines faster, cheaper, and more reliable.

Actionable playbooks to speed up CI/CD: caching, parallelization, test splitting, Docker layer caching, and reliability patterns. Plus step-by-step how-tos for the things teams set up most.

Speed up CI

Caching, parallelism, test splitting, slim images.

How GitHub Actions caching worksHow actions/cache stores and restores dependencies, what the 10 GB per-repository limit and 7-day eviction Cache Docker layers in ActionsMake Docker builds reuse layers between CI runs with buildx cache backends, including why the naive gha cache Cache Rust/cargoCache Cargo registry, git deps, and the target directory in GitHub Actions so Rust CI stops recompiling the Speed up Actions cold startsQueue time, runner boot, checkout, toolchain setup and install run before your first real step. Shard tests across runnersSplit a slow test suite across parallel CI jobs, with the arithmetic for how many shards are worth it and the Speed up Docker buildsMake Docker image builds in CI fast: BuildKit layer caching, registry cache, multi-stage builds, ordering Speed up GitHub ActionsMake GitHub Actions faster: caching, parallelization, test splitting, Docker layer caching, slimmer images, Speed up JestMake Jest fast in CI: tune workers, shard the suite, enable the Jest cache, and run only tests affected by

Make CI reliable

Flaky tests, retries, and self-healing patterns.

Reduce CI flakinessMeasure your flake rate, classify failures into the four causes that actually occur, and fix them at source.

How-to guides

OIDC, secrets, matrix, services, reusable workflows.

Choose a runner sizePick a runner size from measurement rather than guesswork. Most CI jobs are single-threaded, which means more Reclaim Docker disk spaceReclaim disk from unused Docker images, stopped containers and orphaned volumes, with the difference between Clear the Docker build cacheDelete the Docker build cache with builder prune and buildx prune, see how much space it is using, and Run Actions on ARMARM runners are cheaper per minute across every provider. What actually breaks when you switch, how to build

Diagnose CI

Why is my CI slow, expensive, or flaky.

Stuck on "queued"GitHub Actions jobs stuck on "queued" and not starting? The causes - outages, concurrency, runner labels,

Explore other topics

GitHub ActionsWorkflow, runner, and YAML errors - diagnosed and fixed. Node.js & npmnpm, yarn, and pnpm failures in CI - solved. DockerBuild, run, compose, and registry errors - explained. Pythonpip, poetry, venv, and pytest failures - fixed. Java & JVMMaven, Gradle, and JVM failures in CI - resolved. GoGo build, module, and test failures - diagnosed.