Designing efficient ETL workflows in Airflow involves implementing various optimizations to enhance the speed, reliability, and cost-effectiveness of data pipelines. Key strategies include ensuring tasks are idempotent and atomic to maintain data consistency and facilitate error handling. Structuring Directed Acyclic Graphs (DAGs) into smaller, focused workflows improves monitoring and troubleshooting, while leveraging Airflow's parallelism capabilities allows multiple tasks to run concurrently, reducing execution time. Utilizing task-optimized compute environments and efficient data formats like Parquet or Avro can further optimize resource use and speed up processing. Effective error handling, such as setting retries and using alerts, enhances resilience, and scalable backends like Celery or KubernetesExecutor support workload management. Hosted solutions like Astronomer offer features like worker queues and auto-scaling to simplify these processes, promoting a robust and adaptive ETL pipeline management framework.