When SMB signing is enabled, all CIFS communications to and from Windows clients experience a significant impact on performance, which affects both the clients and the server (that is, the storage system running Data ONTAP).
The performance degradation shows as increased CPU usage on both the clients and the server, although the amount of network traffic does not change.
Depending on your network and your storage system implementation, the performance impact of SMB signing can vary widely; you can verify it only through testing in your network environment.
Most Windows clients negotiate SMB signing by default if it is enabled on the server. If you require SMB protection for some of your Windows clients, and if SMB signing is causing performance issues, you can disable SMB signing on any of your Windows clients that do not require protection against replay attacks. For information about disabling SMB signing on Windows clients, see the Microsoft Windows documentation.