Note that the postgres benchmark numbers passed around (most based on my benchmarks) are readonly. For write based workloads the overhead is likely going to be

Note that the postgres benchmark numbers passed around (most based on my benchmarks) are readonly. For write based workloads the overhead is likely going to be much smaller in nearly all cases, there's just more independent workload. The overhead in the readonly load profiles comes near entirely from the synchronous client<->server communication, if you can avoid that for workloads (using pipelining, other batching techniques) the overhead's going to be smaller.