Caching, which is performed through utility functions (add_cache_files and reset_cache_files), helps you speed up the execution of a step by preserving and restoring packages and dependencies between the runs of that step. Avoiding repeating the installation or loading of large dependencies every time the step is run helps in reducing build times. In addition, native steps perform caching as needed and always execute as fast as possible.
For more information, see Caching Step Runtimes.