Almost exactly a month ago, Windows 10 Build 10240 was released to both Fast and Slow. This build served as the milestone for an everyperson's operating system, and it gave OEMs something to validate drivers and software against. According to BuildFeed, the first known branches at that build number were compiled on July 9th.
Today, Windows Insiders on the Fast ring will receive Build 10525 when they next perform a Windows Update. This build was first compiled last week on August 12th, and it represents the first published milestone of the TH2 branch. It contains two new (advertised) features: extra color options for Windows UI elements and improvements to Windows 10 memory management.
I'll talk about Memory Manager first.
As Windows 10 builds were released, there was one where I noticed the System process begun to use a significant amount of RAM — a whole gigabyte or two. I figured that this was a memory leak that would be fixed in a later build, so I put up with it. Some time later, I noticed that its usage would actually go up and down as I open or close applications. It was also never “fixed” before release.
It turns out that it was an intended feature.
When operating systems decide that a chunk of memory is unlikely to be used, they tend to push them to the hard drive. This could be an application that has been minimized for a while, or portions that were displaced by a big, RAM-hungry program. You will often see this when you switch programs. Sometimes, there's a program that's already open, albeit minimized, but it still takes a few seconds to pop up. This behavior is often because it was pushed out of system memory and Windows (or Mac, Linux, and so forth) wasn't prepared to abruptly fetch it again.
Now, system memory is big and cheap, and Windows is being installed on devices with small banks of flash storage and relatively fast processors. Microsoft now believes that it makes sense to cram old chunks of memory into a container, which resides in RAM, that is compressed (as opposed to just dumping it onto permanent storage). This occurs in the system process, which explains why it tends to inflate when you're doing a lot of things at once.
Build 10525 tweaks this feature a bit in undescribed ways. I could imagine that Microsoft cut development in the public branches to make it robust for Windows 10's launch. They now have an opportunity to point Insiders to the less tested branches.
I think this is interesting, and could make a lot of sense if they successfully manage data into their most efficient storage locations. I do notice that System tends to get large even when a lot of RAM is still available. For instance, I have 55% of my memory unallocated at this point, but System is about 1.2 GB large. There could be very good reasons for this, which might be something that my operating system would know better than I, but it might also be a sign that it's slightly over-aggressive. Maybe my system could benefit from a big, contiguous chunk of available memory, or maybe my PC is being unreasonably taxed. Who knows.
The other major feature is color management. While the three displayed toggles are available in 10240, the user is apparently now able to adjust more colors. Without installing 10525, I cannot figure out what those changes are, but Microsoft asserts that they're there.
If you register as a Windows Insider Fast Ring user, you can now receive 10525.