For comparison, skipping dotnet run and running the compiled program directly:
time "/Users/bouke/Library/Application Support/dotnet/runfile/hello-world-fc604c4e7d71b490ccde5271268569273873cc7ab51f5ef7dee6fb34372e89a2/bin/debug/hello-world" > /dev/null
real 0m0.051s
user 0m0.029s
sys 0m0.017s
So yeah the overhead of dotnet run is pretty high in this preview version.