Running NI-MAX GUI in background somehow improves my CAN BUS simulation timing

Hi,  

 

I have a simulation where the UUT sends a CAN message (2-bytes) to my simulation. My simulation process it and returns a 7-byte response message. This has to be done within 10msec, otherwise the UUT reports timeout. When the NI-MAX GUI is running in the background the response time is less than 3msec. If I close the NI-MAX GUI the response time exceeds 10msec. Is there something I`m missing in configuring the CAN card that the NI-MAX GUI is performing?  

 

CAN Card: NI-PCI 8512 Driver: NI-CAN 17.0 and NI_XNET 17.5.1  

 

Thank you, Umesh