When Microsoft released its Windows 10 operating system, it introduced a number of under-the-hood changes. One of these changed how updates were provided to Windows 10 PCs.
Up until the release of Windows 10, Microsoft released individual updates for its systems. While that gave administrators excellent control over the updates, as they could pick the ones that they wanted to install, it meant that a large number of updates had to be installed when an operating system like Windows 7 was installed after a number of years.
Microsoft tried to limit this with the release of Service Packs. These could be installed instead of all earlier updates, which improved the speed and stability of the installation process.
Cumulative updates entered the Windows world in 2015
Microsoft introduced cumulative updates with Windows 10 in 2015. It later introduced the system to earlier operating systems.
The idea was simple: instead of releasing individual updates, Microsoft would release updates that included all previous updates.
Instead of having to install dozens of updates, in some cases hundreds, Windows administrators would simply install the latest cumulative update and they would be done with the updating for the most part.
A new problem emerged: Cumulative updates reduced the number of updates that needed to be installed. However, since they included all previous updates, they grew in size over time.
Surprisingly though, this did not mean that systems downloaded full sized updates each month. Microsoft used a technique called differential downloads, or express updates, to deliver updates to Windows 10 systems.
This meant, that Windows Update downloaded only the update bits that were new. Everything that was installed already was skipped, which increased the updating speed.
The cumulative update model caused four major issues:
- While computers only downloaded the update bits they needed, they had to compute which updates they were missing and do a lot of unpacking, verifiying and merging.
- Fresh installs or factory resets take a long time. Computers had to download a massive update in the beginning, which would take long to install.
- The system caused the WinSxS folder to bloat over time, which could result in storage problems on the main drive.
- Storage was still a problem for, mostly, Enterprise customers who hosted and distributed updates from company servers.
Checkpoint updates come to the rescue
Microsoft introduced checkpoint updates in Windows 11, version 24H2. The main idea was to introduce updates regularly that would reset the cumulative updates.
They take a cue from service packs by creating new start points for cumulative updates. This addressed the major issues that Microsoft identified, e.g., instead of computing changes from the very release of the operating system, the processor would only have to do so from the last checkpoint update release.
Updates should install faster on recent versions of Windows 11 because of this. They also deal with the other problems mentioned, by reducing WinSxS storage or providing smaller, less CPU-taxing updates during fresh installs or resets.

I think this has made a negative change, but I’m not entirely sure. If one needs to fix his/her computer using the in-place repair install method using an .iso, the .iso must be the exact same version/numbering as what is on the computer.
One can’t download any 25H2 .iso and expect to complete a “repair install.” It doesn’t work unless it’s the same version, and the versions change with each new update, even a small one.
MS did make available a Reinstall Option for the entire computer keeping all files, folders and applications, but that doesn’t work so well, either–and it takes forever! [It didn’t fix the problem for me.]
The only way to eliminate a seemingly minor annoyance was to complete a fresh installation. I always like those–throwing away all the garbage accumulated over one or two years–should be a mandatory practice.
With bookmark managers and password managers and programs like Uniget–it’s so much faster than years ago.
@VioletMoon
You can still ‘build’ an ISO that matches your exact build number even if your not on 25H2.
https://pureinfotech.com/windows-11-24h2-iso-download-after-25h2/
Quite the coincidence, you mentioning this.
I’m currently on: Win 11 Pro – 24H2 – 26100.6584.
My WinSxS folder is, “Size: 9.99GB – Size on Disk: 5.99GB”. Is there a way to clean that out? I tried the disk cleanup including system files. (I made a shorcut to it since they hid it)
My “C:” drive is a 145GB partion. I use the rest of that 1TB nVME for some of my games that load large amounts of data from the drive often.
A couple of links–looks like DISM has a couple of commands that help:
Like Option Four–Reset Base:
https://www.elevenforum.com/t/analyze-and-clean-up-component-store-winsxs-folder-in-windows-11.7597/
MS Article:
https://www.elevenforum.com/t/analyze-and-clean-up-component-store-winsxs-folder-in-windows-11.7597/
May be advantageous to have a full system image before tinkering.