In MongoDB serverStatus(), what is the meaning of "connection data handles currently active"?

When running db.serverStatus() in the MongoDB shell (3.4, WiredTiger), the results contain the following data: { "connection data handles currently active" : 94862, "connection sweep candidate became referenced" : 0, "connection sweep dhandles closed" : 91885, "connection sweep dhandles removed from hash list" : 648514, "connection sweep time-of-death sets" : 1514067, "connection sweeps" : 40077, "session dhandles swept" : 110175, "session sweep attempts" : 710643 } What is the meaning of "connection data handles currently active"? Does it have an impact on the instance's performance?