Not only Go compiler is not as good at optimisation as C/C++/Rust/Zig/D compilers, but also Go FFI to C has significant overhead, which means there is often not

Not only Go compiler is not as good at optimisation as C/C++/Rust/Zig/D compilers, but also Go FFI to C has significant overhead, which means there is often not much point in using low-level Linux APIs for performance advantage. Same problem like with Java. And in a database system you quite likely want a fine degree of control with non-standard stuff.