GitHub Actions, a continuous integration and delivery platform, can be optimized using caching to reduce time and cost associated with frequently running workflows. Caching package manager dependencies, such as those managed by npm, Yarn, Python, Java, Ruby, and Go, prevents the need to download fresh packages for every workflow run, thereby speeding up processes. This efficiency is achieved through the cache action, which allows for the saving and reusing of files that rarely change. The article details how to implement caching in GitHub Actions, using Yarn as an example, and highlights the difference between caching and artifacts, emphasizing that caching is suited for static files while artifacts are for dynamically generated files. It also introduces Earthly, a tool that complements GitHub Actions by facilitating local builds and providing more aggressive caching options without the risk of stale cache keys. With Earthly, developers can achieve faster build speeds, enhanced consistency, and local testing capabilities, offering a robust solution for managing complex workflows.