So -- m3.large ec2 instances have a few problems with them. 1, your only running a 2 core machine (1 worker, and assuming 1 broker to distribute through redis). That is not nearly enough to handle really a real-time chat server where everyone is spamming it all the time. Another issue is the network performance of an m3.large instance -- its moderate (which is another word for not very good).<p>With 2 c4.8xlarge instances behind ELB, we consistently see between 20 to 50K active connections on live meetings, and the servers sit at &lt; 2% usage. Latency between event cycles is &lt; 0.015ms.<p>I see a lot of people having problems with this, but the issue is usually the resources they give to it, or the actual handling of socket events. If the socket server is just a relay there should be no reason a single m4.4xlarge instance cant handle 600K+ connections.<p>www.jayway.com&#x2F;2015&#x2F;04&#x2F;13&#x2F;600k-concurrent-websocket-connections-on-aws-using-node-js&#x2F;