Editor's Note: Microsoft has since issued a fix for this issue in Windows 11 Insider Preview Build 25252, with plans to roll the fix out to all Windows 11 users via a monthly update once it's been validated as working correctly. The original story follows.
It's been two weeks since Windows 11 got its big 2022 update (known as 22H2), and some adopters are continuing to report problems post-update. Last week, the Windows 11 update was causing Blue Screens of Death for some users, and now it sounds like Microsoft has pinpointed a bug that's seriously slowing down file transfers for some affected PCs.
According to an official forum post (opens in new tab) from Microsoft's Ned Pyle (brought to our attention by Petri (opens in new tab)), "there is a performance regression in 22H2 when copying larger files from a remote computer down to a Windows 11 computer." As a result, large files may copy as much as 40% slower to an updated Windows 11 PC compared to one that hasn't yet received the 22H2 update. By "large files," we're talking those that are at least several gigabytes or larger.
However, it seems this slowdown most commonly occurs when a PC is transferring large multi-GB files over SMB (Server Message Block protocol) to a Windows 11 PC with the update. So if you're running Windows 11 and recently installed the 2022 update via Windows Update only to find that file transfers from your server (or across your home network if your router happens to rely on SMB) are suddenly much slower than normal, chances are you've been hit by this bug.
According to Pyle, the problem is not actually in the SMB code — file transfers via SMB are simply the most common scenario which causes this slowdown bug. "You could see this behavior even with local file copies not using SMB," Pyle wrote. In other words, the slowdown may occur even when you're just moving files from one folder to another on your hard drive.
How to fix the Windows 11 2022 Update slowdown bug
If you think your PC is affected, Microsoft can offer only a command line string as treatment. According to Pyle, using commands like robocy or xcopy at the Windows command line with a /J parameter at the end should cause the files to transfer at faster pre-update speeds. His example looks like this:
- robocopy \\someserver\someshare c:\somefolder somefile.ned /J
If you'd rather not mess around with command line strings, your only other option is to wait for a fix for this problem. Unfortunately, Pyle says it's unclear when the problem will be solved, as Microsoft hasn't yet managed to pinpoint the issue.
When the company finds a permanent solution, the original Microsoft post will be updated, and we'll update our own story accordingly. If you're encountering other issues with Microsoft's newest operating system, check out our list of Windows 11 problems and fixes for the latest updates on Windows 11's vulnerabilities and what you can do to address them.