Microsoft has finally fixed a known issue causing severe performance loss when copying large files over SMB after installing Windows 11 2022 update.

The bug was fixed with the February 2023 non-security preview update KB5022913 released in February 2022, which also introduced newly announced Moment 2 features.

“This update fixes an issue that affects copying from a network to a local drive. Copying is slower than expected for some users,” Microsoft said.

The fix comes after Microsoft’s Ned Pyle explain in October, “there is a performance reduction in 22H2 when copying larger files from a remote computer to a Windows 11 computer or when copying files to a local drive”.

Although Redmond did not share details on the actual performance drop, according to user reports, the time required for file operations on affected systems could more than double under certain conditions.

“You are most likely to experience this issue copying files to Windows 11, version 22H2 from a network share via Server Message Block (SMB), but local file copying may also be affected”, Microsoft added in a September update to the KB5017389 preview update support document.

Two months later, in November, the company started testing a fix which has been deployed to select systems enrolled in the Windows Insider Program running Windows 11 Preview Build 25252.

Workaround available

KB5022913 allows Windows administrators to test improvements and bug fixes that will be rolling out to all Windows users with next month’s Patch Tuesday.

However, this is optional and does not contain security updates. You can only install the optional KB5022913 update by clicking the “Download and Install” button after checking for updates from Settings > Windows Update.

You can also manually download and install the KB5022913 update for your platform from the Microsoft Update Catalog.

Microsoft has also shared an interim fix that affected customers can use to work around the file copy performance impact.

Users can mitigate the known performance issue affecting copying files over SMB by using file copy utilities that do not use a cache manager (buffered I/O).

Two of the available options include the built-in robocopy and xcopy tools with the model commands listed below:

robocopy \\someserver\someshare c:\somefolder somefile.img /J

OR

xcopy \\someserver\someshare c:\somefolder /J