Is there an actual problem showing up on your client? That looks like a pretty normal sequence, the received operations are still getting executed and returning success.
There is an actual problem (intermittent hanging of the authentication process under load) but I have nothing more than anecdote to tie it to the deferrals. At this point they are the only lead I have. I'm hoping that whatever the client's doing to cause the deferrals is, eventually, producing the auth failures.
-Ben