Windows 11 22H2 bug can slow file downloading by 40%

Downloading and even copying local files may be as much as 40 percent slower using Windows 11 22H2, a Microsoft program manager has confirmed.

Ned Pyle, a principal program manager at Microsoft, wrote that there is a performance regression in Windows 11’s 2022 Update (22H2) when copying files from a remote computer using the Server Message Block (SMB) protocol. The performance hit was unearthed by Petri.com.

It’s not entirely clear whether copying files will slow down when downloading them from a remote server, or merely accessing them from a remote PC. Microsoft doesn’t appear to know quite yet, either. “The issue is not actually in SMB code, so I can’t give you an ETA for a permanent fix yet; SMB is just the most likely scenario to be noticed,” Pyle wrote. “You could see this behavior even with local file copies not using SMB. We’re working with another team to understand this and get to a permanent solution.”

The slowdown appears to manifest when copying down or downloading “large” (multi-gigabyte) files from a remote machine onto a PC running Windows 11 2022 Update (22H2). Files that are copied to another PC not running 22H2 won’t see the slowdown, Pyle wrote.

There is a workaround. “[U]se robocopy or xcopy with the /J (unbuffered IO) parameter,” Pyle wrote, like so:

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

Last week, Microsoft reported a printer bug that manifested when printers were unable to communicate their advanced features to a host PC, which prevented those features from working. Microsoft blocked users with the issue from upgrading to 22H2.