If you have any data (or better yet, benchmarks I can run on my own machine), I'd very much like to see some hard numbers.
Benchmarks are hard to do right but this one does actually measure GC quite well: https://benchmarksgame-team.pages.debian.net/benchmarksgame/... (For managed languages. It is not really a fair comparison between non-GC and GC-languages)
So all in all, for bigger programs it is hard to do a good comparison, but there is exactly where JIT compilers shine and the memory tradeoff and the like brings their return.
It seems like it's a pretty good option to have your infrastructure code implemented in a systems programming language like C or Rust (probably AWS or GCP is doing this for you), and just implement your business logic in Go as the type of small, well-defined programs you're talking about.
If you look at other examples on that site, Go and Java are roughly the same, but with some variance:
https://benchmarksgame-team.pages.debian.net/benchmarksgame/...
The source code is shown —
binary-trees Java #7 program
binary-trees Go #2 program
Regarding concurrency, I wouldn’t choose existing reactive frameworks and what not for a new system. Java will soon get Project Loom, which will introduce Go-like virtual threads - so that one can write a web server that spawns a new thread for each request as well. Since the Java ecosystem is very purely written almost exclusively in Java itself (no FFI), basically everything will turn automagically non-blocking.