"outside of Unity"
Because unity is not yet on CoreCLR. But unity shouldn‘t be much different to other applications. Jetbrains moved Rider only a few years ago to .NET Core, and everything became much snappier (it was on on .NET 4.x on windows and on mono for Linux/Mac before, which was even slower than the windows only full framework)
[1] https://forum.unity.com/threads/performance-optimizations-fo... [2] https://forum.unity.com/threads/expected-performance-of-new-...