Answer:

After starting each sampling session Foxhound waits 2 seconds before starting the next one in order to prevent performance problems within Foxhound itself.

For example, if Foxhound itself is shut down and restarted, and there are 100 separate target databases for it to monitor, it will take at least 99 * 2 seconds = 3 minutes and 18 seconds for Foxhound to restart all 100 monitor sessions.