QLogic HBA is slower than SW Initiator

Hello folks,

I am using a QLogic QLE4062c HBA in my ESXi 5.1. When testing perfomance, I get 85 MB/s read and 75 MB/s write. When I test the same volume with ESXi software initiator, I get a nice 106 MB/s read and write.

As a side note: I am using the same QLogic HBA in a non-ESXi server and I get 100 MB/s read and write.

I always tought HBA get better perfomance than software initiator. Why do I lose that much? Are there some know issues? Do you have an idea how I can tweak things up?

Thanks in advance.