Yeah I don't get this argument either. It's like people are still stuck in micro-benchmark-land. Sub-1ms responses are the norm in Phoenix and I tend to never get anything above 100µs for LiveView messages, sure, they're noops, but calling it slow is .. well, strange.
Sure, you don't want to do number crunching in pure Elixir, but I'm always curious as to the actual needs people have, once being one of the "performance is everything" kind of developers myself.