[German]On May 13, 2025, Microsoft released the cumulative security update KB5058411 for Windows 11 24H2 and Windows Server 2025 (24H2). This has the incredible size of 4368.9 MByte. This raises the question of what makes the update package so bloated? Spoiler: It's the AI stuff that Microsoft is including in the update.
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Update KB5058411 is 4368.9 MByte in size
Shortly after the release of the May 2025 security updates for Windows, a German blog reader got in touch and asked if anyone knew why the security update KB5058411 for Windows 11 24H2 was around 4 GB in size. The cumulative update from April (KB5059087) came with a "slim" size of approx. 800 MB, he wrote.
I checked the Microsoft Update Catalog and found that the downloadable .msu update packages for Windows 11 24H2 and Windows Server 2025 (24H2) in the 64-bit version for Intel CPUs have the incredible size of 4368.9 MB.
Susan Bradley also asked this question on the patchmanagement.org mailing list. There were answers that the size was possibly related to the issue of hotpatching, which was included in the updates for the first time in May 2025. But that's incorrect.
Blame the AI stuff
User abboddi delivered the right answer. You can inspect the content of an update archive, if you unzip a downloaded .msu update file with 7-zip. The files related to the regular update are about 850 MB in size. The archive contains around 3 GB of files belonging to Microsoft's AI apps.
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However, this AI stuff is, according to Microsoft, currently only relevant for the Copilot+PCs with NPU (for AI), as the AI features are only supposed to be installed and updated on this platform, according to the official version.
When I read this, I was a little taken aback, especially as the update is also offered for Windows Server 2025, where AI makes imho no sense. I immediately thought of the topic of optimizing the update size, which Microsoft has repeatedly propagated with puffed-up cheeks.
In November 2021, I mentioned such an optimization in the blog post Microsoft plans to phase out older updates, promises speed and security gains. At that time, Microsoft was once again working on optimizing the cumulative updates for Windows 10 because their size was growing rapidly.
Microsoft's reasoning was that the large update packages cost speed during download and installation. Microsoft therefore came up with the idea of allowing certain older updates to expire cyclically so that these files are no longer included in new cumulative updates. Microsoft hoped that this would improve speed and security.
And now we see that all this must have been "water under the bridge", because Microsoft packs its AI stuff into the .msu update archives and then noodles them onto all systems, regardless of whether they can do anything with them or not? Microsoft may have technical reasons for this approach. But at this point I ask myself: What have I not understood "the beef", or where has Microsoft taken a wrong turn and lost any plan?
Similar articles:
Microsoft Security Update Summary (May 13, 2025)
Patchday: Windows 10/11 Updates (May 13, 2025)
Patchday: Windows Server-Updates (May 13, 2025)
Patchday: Microsoft Office Updates (May 13, 2025)
Windows 10: Cumulative Updates (LCUs) now integrates SSUs
Windows 10 Service Stack Update (SSU) internal explained
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Windows 11: Microsoft optimizes the size of update packages
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the KB5055627 update was also 4.3Gb in size for x64 system & 3.0Gb in size for arm64 system:
https://www.catalog.update.microsoft.com/Search.aspx?q=kb5055627
so the download major size increase started from KB5055627