HI m_grewnow
Keeping everything 4GB end to end is sometimes not possible due to the age and nature of kit , this should not cause you any performance issues though and the end of the day you'll need to make sure that the workload your pushing back to your Netapp is keeping up.
Do you have any tools with your Netapp to look at Aggreate performance that will give you an indication on how things are running on the Filer , then if you still experiencing problems work your way back to the host.
1. Check stats on aggregate with tools.
2. Check your Fiber switches for any errors.
3.Check your que depth settings on your HBA.
Good luck
David