I am running a private network where nodes add and remove each other dynamically.

I have a problem where, the first time a node performs `admin.addPeer()` to a neighbor the peering is instant (as desired), but after that it can take 10 seconds or more before a connection is established (that is, once `admin.removePeer()` and `admin.addPeer()` are called). 

If I wait long enough, then it becomes instant again.
Could it be a sort of spam protection?

Cheers