You can't optimize anything with C++ if your database is stuck waiting for consensus with nodes 100 ms away. Close to the metal and low level languages are really poor choices here, even Go is too low level for CP databases.

Yes, but you'll have lower overhead on each query/request and more concurrency ? For each query the bottleneck is the network which you can't fix, but you can fix the 2,3,etc bottlenecks which are inside 1 machine (cpu/ram/disk).

Yeah...I'm not really aware of a higher level language that mystically makes networking faster. As far as I'm aware, the most efficient network protocols tend to be implemented at a low level, too.

> C++ still seems preferable in these types of applications

Agreed, but until there are some published performance metrics, I think it's an assumption more than a truth. Premature optimization...

Well we already have metrics on what the languages themselves can do. And given that performance will definitely matter in this domain, it's not a premature optimization at all. A database isn't something that can be written easily enough to simply rewrite it in another language later as an optimization.