They mention this in the update:

Update: A few people have mentioned that Node by default will use maxConnections of 5, but setting it higher would make NodeJS run much quicker. As I said, im sure NodeJS could go faster - I would never make assumptions about something I don't know much about - and the numbers reflect that suggestions. Removing the blocking PHP approach (because obviously it's slow as shit) and running just the other three scripts looks like this: