Visual Studio grinds to a halt when upgrading a netcore website

This cost me the better part of a day to investigate since I tried everything else but recreating the project.

How I messed up

I had an ASP.NET Core WebApi project that I simply upgraded to .NET Core 2.0 by changing a line in the configuration from

<TargetFramework>netcoreapp1.1</TargetFramework>

to

<TargetFramework>netcoreapp2.0</TargetFramework>

What happened

Visual Studio (2017) pretty much hanged and/or performed extremely slowly. When loading the solution VS took about 2 minutes to load the web project.

How did I resolve it

Simply recreate the web project (with 2.0 selected) and import all files to it again. Pay a little notice to the startup.cs file. You might find some small changes there so don't just overwrite it.