It is apples-to-apples if you're comparing cost, which (I think) is what UA really cares about. But they didn't do the math explicitly and, like you, I was curi

It is apples-to-apples if you're comparing cost, which (I think) is what UA really cares about. But they didn't do the math explicitly and, like you, I was curious, so: A small instance costs 8.5¢/hr, so if it handles 35,000 connections with Eventlet that's 0.00024¢/hr/conn. Put another way, that's $57.60 to handle a million connections for a day. A large instance costs 34¢/hr, so at 500,000 connections that's 0.000068¢/hr/conn, or $16.32 for a million connections for a day. So the NIO implementation apparently saves UA 72% over the Eventlet implementation. Impressive! (This is where I wait for someone from UA to show up and correct my numbers...)