Have you tried giving it a higher cpu share or reservation?
What does the CPU ready values show?
Check for ballooning memory too.
You may want to consider turning hyperthreading off, VMware may be putting your vcpu's on same core and hyperthreading them, cutting your allocation in half.
CPU affinity as a test may help.
I would like to hear your results.
However, over allocation of CPU resources is a problem when you get into multiple vm's. The more CPU's the harder it is to schedule it in a busy host. Especially of the CPU allocation is even close to the number of physical cores.
I have app folks who always wanted 4-8 vcpu's on an 8 core host with 10 VM's. Always drives me crazy. When we got the 24 core blades, CPU ready plummeted by 1000%.
