Earlier today, Microsoft released the Windows 10 May 2020 Update, also known as version 2004. Not as big of an announcement, however, is the release of Windows Server version 2004, which is now available for those in the Semi-Annual Channel (SAC).
You can use the following to get Windows Server version 2004 images from MCR.
docker pull mcr.microsoft.com/windows/servercore:2004
docker pull mcr.microsoft.com/windows/nanoserver:2004
docker pull mcr.microsoft.com/windows:2004
The company boasted an overall smaller size to both the download size and the OS itself, coming in at a 1.865GB download and 4.05GB on-disk. That can be compared to 2.257GB and 4.97GB for version 1909, and 2.311GB and 5.1GB for version 1903. One of the changes made is that the Server Core no longer optimizes the .NET Framework for performance, as that's now done in the .NET Framework runtime image.
Indeed, this update seems to be all about optimizations. A smaller footprint for the OS means a faster startup, optimized performance, and more. Another thing that Microsoft is looking to optimize is Server Core containers. It wants to be able to modernize traditional apps without taking up too much storage space or bandwidth.