We've been working with VMWare on a ticket related to slow upload/download transfers using the VMWare API/SDK on Mac. They believe the root cause is below.  The slow performance is caused by Apple's authentication subsystem (PAM/opendrectoryd) being slow and using a lot of CPU. The security for guestOps file transfer requires an authn check for every packet, packets are limited to ~60k bytes due to the underlying arch; hence every 60k bytes of data has a ~.2 second overhead for the authn. (We see no such delays for Linux or Windows.) Does anyone have any experience with PAM/opendirectoryd who might be able be help me?