The Windows 11 22H2 file copy performance bug could be far worse than first thought

As reports had suggested, Microsoft begun rolling out Windows 11, version 22H2 last month. And as one would expect, it hasn't been a complete smooth sailing.

For example, many users reported that the update was failing with an error code "0x800f0806". Interestingly, one of our Neowin members managed to figure out a workaround for the problem. Then there are the usual suspects, like printer problems, where a new printer policy was leading to printers being not detected post the 2022 Update. Another related issue led Microsoft to block the update altogether on affected devices. Following that, Microsoft issued a word of warning to IT admins as it discovered that provisioning is currently broken for Windows 11 22H2.

In the meantime, the Redmond firm re-visited another issue which led to massive slow-downs in large file copy speeds when done remotely on a 22H2 system. The company said that around 40% lower speeds were being observed. However, users are reporting even worse performance hits.

ivicask, who is a regular on the Microsoft tech community forums, claims they're seeing over a 100% performance hit:

I would just want to correct 40% slower statement from Ned, im seeing way over 100% difference on setups like 10gb NICs (5gb/s vs 2gb/s) difference, or on SMB multi channel setups with multiple gigabit NICs.

While the issue was initially thought to be affecting the Server Message Block (SMB) protocol mainly, Microsoft's Ned Pyle has now confirmed that their initial suspicion was a bit off. Apparently, the problem exists somewhere else:

I can't share too many details yet, but we know exactly where it is getting slower in Kernel, nothing to do with SMB or compression.

Regardless, Microsoft has provided a detailed workaround in case you are struggling against this problem:

Symptom Workaround

Copying large multiple gigabyte (GB) files might take longer than expected to finish on Windows 11, version 22H2. You are more likely to experience this issue copying files to Windows 11, version 22H2 from a network share via Server Message Block (SMB) but local file copy might also be affected.Windows devices used by consumers in their home or small offices are not likely to be affected by this issue.
To mitigate this issue, you can use file copy tools that do not use cache manager (buffered I/O). This can be done by using the built-in command-line tools listed below:

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

or

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

We are working on a resolution and will provide an update in an upcoming release.

Symptom	Workaround
Copying large multiple gigabyte (GB) files might take longer than expected to finish on Windows 11, version 22H2. You are more likely to experience this issue copying files to Windows 11, version 22H2 from a network share via Server Message Block (SMB) but local file copy might also be affected.Windows devices used by consumers in their home or small offices are not likely to be affected by this issue.	To mitigate this issue, you can use file copy tools that do not use cache manager (buffered I/O). This can be done by using the built-in command-line tools listed below: robocopy \\someserver\someshare c:\somefolder somefile.img /J or xcopy \\someserver\someshare c:\somefolder /J We are working on a resolution and will provide an update in an upcoming release.