For loss of performance use a virtual server. If you want a real world solution use BSD Jails.
No matter what you lose performance with a virtual machine. The only people I know who go virtual server are people who bought Vmware`s sales pitch...
The only use I can see for virtual servers is for legacy systems.
Interesting perspective
The impact of virtual versus physical is around 2-10%, depending on the component (e.g. CPU, RAM) measured and the server task. The biggest impact is seen on vdisks with high IO requirements such as databases. So the type of storage used is very important, and it is important that the storage is configured correctly. The (mostly small and unnoticeable) decrease in performance is worth the benefits of virtualising....
Also remember that there is a massive difference between a type one and type two hypervisor....
Perhaps one day I'll show you demo that will make you change your mind