Performance impact of enabling topic statistics

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ROS Topic Statistics are great for monitoring every topic on the system. Tools such as ARNI rely on topic statistics to be enabled at all times during normal operation.

Does anyone know what kind of performance impact there is to having enable_statistics set to True all the time?

Think of the following use case: I want to know the publish stats (frequency, data age) of a high-density Lidar driver output. I could subscribe to the pointcloud using a monitoring node, but this means the monitoring node would receive the entire pointcloud payload even though it doesn't need it. This seems rather inefficient, all it needs to know is if something was published or not and when.

Is that the purpose of topic statistics? a lightweight way to dump out all topic activity?

Just wondering if enable_statistics is something that was designed for debug only or something that could be left on at all times. I also couldn't find a REP that discusses topic statistics, if I missed something, please let me know.

Thanks!