This is a pretty naïve comparison of socket.io implementations in nodejs and erlang.

Here we have two servers that respond "PONG" to any message they receive.
In order to be able to run the nodejs version, you need to have node and its socket.io module installed. You can do that with:

    npm install socket.io
    
In order to be able to run the erlang version, you first need to run:

    git submodule init
    git submodule update
    cd socket.io-erlang
    make

Then just run 'node node.js' or ./erlang. A http server will be started on port 3000.
Note that you can't run both servers at the same time.

In the webpage that will be displayed when you go to http://localhost:3000, you can set a number of messages to be sent to the server via socket.io.
In my computer nodejs processes 10k messages in 1250ms, and erlang version does the same in 1050ms.
With 100k messages, erlang handles them in 70secs, and node drops the connection thus failing the test.

We know that benchmarks aren't really that useful, since they differ from real production code. But this one served me to decide to go with erlang instead of node for a game I will be developing. Not being able to handle 100k messages is a no-no, given that erlang is able to handle them without problem.