when ros statistics send parameters when establish a TCP connection

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We have two ROS nodes: one node called A runs ROS Kinect driver, and can get Kinect data and publish it. One node called B runs some algorithm to Subscribe Kinect data and process it. Two nodes run on different machine.

Now when B start subscribe from A, I can see TCP establishment from wireshark, But I also notice that after TCP was built, there also ROS topic statistics message going on, and below is the list:

I don't understand why this needs to be set, and also it will create the extra big delay when network latency is big, Could anybody help me to understand this and explain why ROS do like this.

/enable_statistics
/statistics_window_min_elements
/statistics_window_min_elements
/statistics_window_max_elements
/statistics_window_min_size
/statistics_window_min_size
/statistics_window_max_size
/statistics_window_max_size
/kinect2/hd/image_depth_rect
/kinect2/hd/image_depth_rect
/kinect2_points_xyzrgb_hd/image_transport
/enable_statistics
/statistics_window_min_elements
/statistics_window_max_elements
/statistics_window_min_size
/statistics_window_max_size
/kinect2/hd/image_color_rect
/enable_statistics
/statistics_window_min_elements
/statistics_window_max_elements
/statistics_window_max_elements
/statistics_window_min_size
/statistics_window_max_size
/statistics_window_max_size
/kinect2/hd/camera_info