Just wrapped up benchmarking in a devcloud. The new code is around 18% slower on average: https://gist.github.com/technomancy/e536dae32cb6f75807d4

Not sure if that qualifies as "pretty close", but it's definitely not off by orders of magnitude. I don't know if we should expect the difference to be more pronounced in a real-world scenario since the process's mailbox was always empty in the benchmark.