I suspect that your sassrv user is configured as an off-host / AD user, and that the authentication required at the operating system level to start a Multibridge session is causing a delay.
Increase the STP Server Start Size to match the number of Multibridge sessions you have defined, and if you're going to depend on this as an operational scoring service, also define some additional Multibridge sessions (assuming current default of 3). Increasing Start Size to match the number of sessions will make sure that STP multibridge processes are authenticated at the OS level and started by the Spawner long before your STP request ever hits them, so that they are ready for execution.
Note on increasing start size and removing the Inactivity Timeout: http://support.sas.com/kb/20/769.html
Note on adding multibridge sessions: http://support.sas.com/kb/30/568.html
@Kurt_Bremser - when you consider the typically 60ms+ round trip from client -> spawner -> metadata -> multibridge -> client, the page faults will be insignificant.
Nik
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