Let's say we are doing data backup on S3 storage and it's taking a lot of time. How would you mitigate this issue? What approaches would you have?

To speed up S3 backups, first enable multipart upload which splits large objects into parallel parts, reducing total transfer time. Use S3 Transfer Acceleration or AWS DataSync for cross-region or large-scale transfers. Implement incremental backups by tracking changed objects with S3 Inventory or versioning, so only new or modified files are copied. Parallelize the backup process by launching multiple threads or processes, each handling a subset of objects. Leverage S3 Select to retrieve only necessary data from large objects, reducing bandwidth. For very large datasets, consider using S3 Glacier or S3 Intelligent-Tiering to archive older data and keep hot data in S3 Standard. Additionally, enable S3 Transfer Manager in SDKs to automatically handle retries and concurrency. Finally, monitor transfer metrics via CloudWatch and adjust the number of concurrent uploads to avoid throttling. These combined strategies can dramatically cut backup times while keeping costs reasonable.