Any news on this one?
I'm on 10.5 yet and I'm seeing similar behaviour.
2 hosts: HP DL380running vsphere 5.1
16 disks per host. 10k RPM 450 GB 2.5inch
One HP VSA per host, 2 vCPU and 5 GB memory per VSA.
Latency is usually very high for VM using the VSA storage. Latency on the physical HBAs is very moderat.
