CentOS, 1 CPU, 4GB RAM runned on VM (based on customer report, tested in 2012):
Customer feedback in __2012__: CentOS, 1 CPU, 4GB RAM runned on VM:
CPU 10%, Memory 15%
6000 xhr-long polling sessions or 15000 websockets sessions
4000 messages per second
Customer feedback in __2014__: "To stress test the solution we run 30 000 simultaneous websocket clients and managed to peak at total of about 140 000 messages per second with less than 1 second average delay." (c) Viktor Endersz - Kambi Sports Solutions