Aaron Bertrand runs some tests:
Whether you are a bank or a hot dog stand, creating backups is a boring but essential part of managing databases. Compressing backups – like other types of data compression – can save time and storage space, at the usually unavoidable cost of CPU. There has been little change in compression throughout SQL Server’s long history, but this year, in SQL Server 2025, there is an exciting change coming.
This set of results from Aaron is a bit different from what we’ve seen from Andy Yun and Anthony Nocentino. That’s a big part of why it’s important to get several data points, and to do your own testing in your own environment with your own equipment.