I'm not sure whether any of that timing precision will do any good on GitHub Actions, where this seems to be running. I don't think the machine is going to be quiet enough to get a good measurement of anything.
Here's something interesting. If I run my test in a RHEL5 (Linux c. 2010) VirtualBox VM then it actually goes faster than a modern Linux kernel running on bare metal, taking only 14µs. If I run it in a RHEL7 VM then it needs 131µs.
So >1ms hello world execution should be a red flag. If that's actually the latency of GitHub's kernels and can't be explained by something like a shell script doing the time interval measurements, then it'd be interesting to learn what it's doing.
Here's the measurement code, it appears to be significantly more complicated than a simple fork/exec/wait loop but that could just be all the C# getting in the way: https://github.com/hanabi1224/Programming-Language-Benchmark... Note that we are definitely measuring the C# async runtime to some degree. Nevertheless you are probably right that the bulk of this 1.8ms is in the executable under test, and it truly is just bloat. Running `hyperfine ./empty-main-function` from rustc on my Mac gives 0.8ms.