Any solution to this?
We have this too.
ESXi 5.0 U2 on HP DL580 G7
Running two Win2008 r2 64bit test VMs with E1000
We have tested several different senarios and bumped into this problem looking for a performance issue.
The strange thing about this is that two equal Linux Debian 6 64bit VMs do just fine in all test cases.
But when monitoring with ipref the Windows VMs performed extreamly poor when on the same vSwitch, within the same VLAN.
Making the parameter change to the cmd-line as sugested here, did the trick.
Why does windows make such poor performance in this test case? Can it be that this also applies to some file transfers and other network traffic as wel?