Whenever I opened UE4.sln, Visual Studio 2017 would start, then hang for about 3.5 minutes before being usable. I had figured this was just due to the sheer size of the UE4 project, but it turns out to be a performance problem with the UnrealVS extension.
The problem was diagnosed by Microsoft in Dec 2018.
I've found two workarounds:
To disable UnrealVS extension: Visual Studio 2017 > Tools menu > Extension and Updates... > UnrealVS

To disable the source control plug-in: Visual Studio 2017 > Tools menu > Options... > Source Control > Plug-in Selection, and then set the Current source control plug-in to None.
The problem was diagnosed by Microsoft in Dec 2018.
I've found two workarounds:
- Disable the UnrealVS extension
- Set the Visual Studio source control plugin to None
To disable UnrealVS extension: Visual Studio 2017 > Tools menu > Extension and Updates... > UnrealVS
To disable the source control plug-in: Visual Studio 2017 > Tools menu > Options... > Source Control > Plug-in Selection, and then set the Current source control plug-in to None.
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