Microsoft has released a new Insider Preview build of the Windows Server VNext Semi-Annual Channel edition

What’s New
Windows Server Core Container Images Are 20% Smaller
In what should be a significant win for any workflow that pulls Windows containers images, the download size of the Windows Server Core container Insider image has been reduced by 20%. This has been achieved by optimizing the set of .NET pre-compiled native images included in the Server Core container image. If you are using .NET Framework with Windows containers, including Windows PowerShell, use a .NET Framework image, which will include additional .NET pre-compiled native images to maintain performance for those scenarios, while also benefiting from a reduced size.

  Windows Server vNext Insider Preview Build 19008 released