Virtualization has become a hot topic. Cloud computing is the latest and most prominent application of this time-honored idea, which is almost as old as the computing field itself. The term "cloud" seems to have originated with someone's drawing of the Internet as a puffy cloud hiding many servers and connections. A user can receive a service from the cloud without ever knowing which machine (or machines) rendered the service, where it was located, or how many redundant copies of its data there are. One of the big concerns about the cloud is that it may assign many computational processes to one machine, thereby making that machine a bottleneck and giving poor response time. Faouzi Kamoun addresses this concern head on, and assures us that in most cases the virtualization used in the cloud and elsewhere improves performance. He also addresses a misconception made prominent in a Dilbert cartoon, when the boss said he wanted to virtualize the servers to save electricity.