I have a new blog post up at HouseOfBrick.com on why you should understand your workload performance characteristics. When you virtualize, allocate the proper amount of resources to the VM instead of just arbitrarily assigning lots of vCPUs and vRAM without reason. Check it out!
http://www.houseofbrick.com/component/content/article/1/175-Right-Sizing-Your-Virtual-Machines