Starting in version 3.50 Avalanche combined virtual cores into single port to easy configuration replacing the old 'virtual port' requirements.
For the Spirent TestCenter CM card module there are 3 virtual cores for each physical port. This requires 3 or more IP addresses to activate all 3 virtual cores. If only a single IP is configured only 1 core would be enabled resulting in lower performance.
The above is valid for all cards or appliances that have multi-core ports such as the CPU cards, 10G ports et al.
Solution is to ensure the subnet IP address range has a minimum of 1 IP per core in use, configured on the client/subnet and server/subnet tabs.
Sample performance tests can be generated from GUI->Tools->Generate Performance tests and can be used as templates for custom configurations.