I can also confirm the overhead on Windows 11 (it's a simple Console.WriteLine)
> Measure-Command { dotnet run run.cs }
Days : 0
Hours : 0
Minutes : 0
Seconds : 2
Milliseconds : 451
Ticks : 24511653
TotalDays : 2,836996875E-05
TotalHours : 0,00068087925
TotalMinutes : 0,040852755
TotalSeconds : 2,4511653
TotalMilliseconds : 2451,1653
IME, windows defender hates compilers. When I run my big C++ project, Defender consumes at least 60% of the CPU. Even when exempting every relevant file, directory, and process.
Task manager doesn't show it, but process explorer shows kernel processes and the story is quite clear.