The driver works but the transmit and/or receive data rates are not optimal.
These recommendations may assist with gaining immediate improvement:
For best performance practices, please refer to the "Performance Tuning Guide for NVIDIA Network Adapters".
Out of the box throughput performance in Ubuntu14.04 is not optimal and may achieve results below the line rate in 40GE link speed.
IRQ affinity is not set properly by the irq_balancer
For additional performance tuning, please refer to Performance Tuning Guide.