Now I'm more confused. An infinitely efficient system would saturate the network. An infinitely inefficient system would saturate the CPU. " The implementation saturates CPU before reaching I/O limits." is true infinitely inefficient system, but false for an infinitely efficient system. That means it's an undesirable.

The metric that actually matters is efficiency of the task, given a hardware constraint. In this context, that's entirely network throughput (streaming ability/hardware, with hardware being constant, you can just compare streaming ability directly).

For a litmus test of the concept, if you rewrote this in C or Rust, would the CPU bottleneck earlier or later? Would the network throughput be closer or further from its bottleneck?