Slow Docker on Windows Run Step, Why? : <p>I'm trying to create a new docker image with the following <code>dockerfile</code>, but it's taking an awful long time to finish one of the steps:</p>

<pre><code>FROM microsoft/dotnet-framework:4.7

SHELL ["powershell"]

# Note: Get MSBuild 12.
RUN Invoke-WebRequest "https://download.microsoft.com/download/9/B/B/9BB1309E-1A8F-4A47-A6C5-ECF76672A3B3/BuildTools_Full.exe" -OutFile "$env:TEMP\BuildTools_Full.exe" -UseBasicParsing
RUN &amp;  "$env:TEMP\BuildTools_Full.exe" /Silent /Full
# Todo: delete the BuildTools_Full.exe file in this layer

# Note: Add .NET 
## RUN Install-WindowsFeature NET-Framework-45-Features ; \

# Note: Add NuGet
RUN Invoke-WebRequest "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe" -OutFile "C:\windows\nuget.exe" -UseBasicParsing
WORKDIR "C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v12.0"

# Note: Add Msbuild to path
RUN setx PATH '%PATH%;C:\\Program Files (x86)\\MSBuild\\12.0\\Bin\\msbuild.exe'
CMD ["C:\\Program Files (x86)\\MSBuild\\12.0\\Bin\\msbuild.exe"]
</code></pre>

<p>Here is the output so far:</p>

<pre><code>PS C:\MyWorkspace\images\msbuild&gt; docker build -t msbuild .
Sending build context to Docker daemon   2.56kB
Step 1/9 : FROM microsoft/dotnet-framework:4.7
 ---&gt; 91abbfdc50cb
Step 2/9 : MAINTAINER mohamed.elkammar@gmail.com
 ---&gt; Using cache
 ---&gt; fbf720101007
Step 3/9 : SHELL powershell
 ---&gt; Using cache
 ---&gt; 642cf0e08730
Step 4/9 : RUN Invoke-WebRequest "https://download.microsoft.com/download/9/B/B/9BB1309E-1A8F-4A47-A6C5-ECF76672A3B3/BuildTools_Full.exe" -OutFile "$env:TEMP\BuildTools_Full.exe" -UseBasicParsing
 ---&gt; Using cache
 ---&gt; a722c88fee0f
Step 5/9 : RUN &amp;  "$env:TEMP\BuildTools_Full.exe" /Silent /Full
 ---&gt; Using cache
 ---&gt; 4fda7448f2e4
Step 6/9 : RUN Invoke-WebRequest "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe" -OutFile "C:\windows\nuget.exe" -UseBasicParsing
 ---&gt; Running in eec036874574
</code></pre>

<p>Additionally, here is the output of <code>docker info</code>:</p>

<pre><code>C:\Windows\system32&gt;docker info
Containers: 2
 Running: 1
 Paused: 0
 Stopped: 1
Images: 5
Server Version: 17.06.1-ee-2
Storage Driver: windowsfilter
 Windows:
Logging Driver: json-file
Plugins:
 Volume: local
 Network: l2bridge l2tunnel nat null overlay transparent
 Log: awslogs etwlogs fluentd json-file logentries splunk syslog
Swarm: inactive
Default Isolation: process
Kernel Version: 10.0 14393 (14393.1715.amd64fre.rs1_release_inmarket.170906-1810)
Operating System: Windows Server 2016 Datacenter
OSType: windows
Architecture: x86_64
CPUs: 1
Total Memory: 4.75GiB
Name: instance-1
ID: B2BG:6AW5:Y32S:YLIO:FE25:WWDO:ZAGQ:CZ3M:S5XM:LSHB:U5GM:VYEM
Docker Root Dir: C:\ProgramData\docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false
</code></pre>

<p>What would cause a simple download step to take forever?</p>
