Here’s an update from @apenney on the thread I opened over on elixir-lang-talk:
Just a quick note from someone that tried (and failed) to get acceptable performance numbers from Elixir.
You should check into wrk2 instead of wrk1 for your testing. The reason being that wrk1 has a “coordinated omission” problem whereby the tool and the service accidently conspire to produce nicer numbers!
Wrk2 will send traffic at a steady rate instead of “when it can”, which often results in drastically different numbers. I was seeing latency in the seconds at the 99th percentile with wrk2 and a quick test with just plug.
When we tested our own scala based service internally we went from seeing 100ms at 100% to 9 minutes with wrk2, so it was quite an eye opener!
Sad that there wasn’t a happy ending 
