Problem With Network Adapter

Hello every body

I have a PC (dell Optiplex 7010) with a Built in network adapter Intel 82579LM

I installed ESXi 5.1 on the PC and It work Fine

After this i decided to add another network adapter to increase the VMs

So I added the Dlink 528T and installed it as specified in this topic

http://www.nvizor.com/?p=813

after this i added a new network and assigned a new adapter to this network as it explains in the pictures

At this point there is no problem

The problem started when i tried to copy any file (TO/From) any VM on the Dlink Network (vSwitch 1)

The Maximum transfer Rate I reached when copying any file FROM a VM on Dlink Network is 32 MBpS

and Maximum Rate 80 MBpS when copy any file TO a VM

Once I changed the network adapter to this VM to the VM network (vSwitch 0) the transfer Rate Jump to 112 MBps

Briefly the VMs works on the DLINK card didn't  exceed 80 MBpS when copying to it and 32 MBpS when copying From it.

What is the problem and how i can fix it