Currently the CLI runs everything in serial on the same thread (main), work is in progress to offload the validation to workers and let the CLI run multiple workers in parallel. The gist of the required changes: * Create and run CLI workers running the actual validation * New `--workers` option to control number of workers. * Offload both configuration loading and validation to workers. The preference would be if the main thread holds the full queue of files to validate and dispatching jobs once a worker is free, in contrast to just splitting the queues into equal sized chunks. The rationale is that some jobs takes much longer. Note: only the CLI will be parallelized, user of the API will have to implement this themselves if needed.