Thanks for the reproducable bug report... I get the same behavior, so
long as the packets are small enough.. above 10k or so I don't see
this behavior.  This looks like like Nagel's algorithm at work, try
setting TCP_NODELAY on the subscriber, like this:

#include <ros/transport_hints.h>
ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback,

ros::TransportHints().tcpNoDelay());