Microsoft fixes Windows 11 slow file copy issues over SMB

Microsoft has finally addressed a known issue caused by the Windows 11 2022 Update that slowed down the copying of large multiple gigabyte (GB) files over SMB (Server Message Block) protocol.

The bug was fixed with the KB5022913 February 2023 non-security preview update released in February 2023, as part of the Moment 2 patch.

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

More On The Windows 11 2022 Update Bug

In September last year, Microsoft officially announced the general availability of Windows 11, version 22H2.

Following the availability, the company confirmed that a bug is affecting multi-GB files and reducing throughput by up to 40% less than the regular speed over SMB after installing the Windows 11 2022 update (Windows 11 version 22H2).

“There is a performance reduction in 22H2 when copying larger files from a remote computer down to a Windows 11 computer or when copying files on a local drive,” explained Microsoft’s Ned Pyle when acknowledging the issue in early October last year.

“A large (multi-GB file) might see as much as 40% less throughput over SMB when copying down (reading). Copying that same file to a non-22H2 machine (writing) won’t see this problem.”

In November 2022, the company started testing a fix and rolled it out to some systems enrolled in the Windows Insider program running Windows 11 Preview Build 25252, while confirming that the hotfix would be released to the public in a monthly update.

“The preview fix for this issue is now available in Windows 11 Insider Preview Build 25252,” Pyle noted. “The final fix for Windows 11 22H2 production computer will come in a normal monthly Cumulative Update through Windows Update once validated in Insider builds.”

While Redmond did not provide any information on the actual decrease in performance on affected systems, although some user reports indicated that the time needed for file operations on affected systems could more than double in some cases.

The fix is now included in Windows 11 22H2 Moment 2 update (KB5022913 optional update) and will roll out to all Windows users via March 2023’s Patch Tuesday release.

However, the KB5022913 optional update does not include security updates. It can only be installed by clicking the “Download and install” button after checking for updates in Settings > Windows Update, or by manually downloading and installing it on the system from the Microsoft Update Catalog.

Additionally, Microsoft has also provided a temporary workaround that affected customers can use to mitigate the known performance issue impacting file copying over SMB.

In order to avoid the performance hit issue, users can use file copy utilities such as built-in robocopy and xcopy tools, which don’t employ cache manager (buffered I/O) with the template commands listed below:

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


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

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Kavita Iyer
Kavita Iyer
An individual, optimist, homemaker, foodie, a die hard cricket fan and most importantly one who believes in Being Human!!!


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