Using Application Virtualization in a VDI environment add a lot of flexibility to the administrator by separating applications from OS images. However, as with all virtualization solutions, this advantage comes at a performance cost. Sven Huisman, Jeroen van de Kamp and Ruben Spruijt have concluded phase IV of Project Virtual Reality Check (Project VRC) to address the impact of various use cases for application virtualization in a VDI environment and how each major vendor fares performance-wise in testing these use cases.
Depending on the use case scenario, Project VRC discovered that this impact can be significant. Test results show that Application Virtualization has impact on the VDI user density, which can be decreased by 20% to 45% when Office 2007 is completely virtualized. This should be considered as a worst case scenario. When only a couple of specific (business) applications is virtualized, the session density decreases by only 3 to 12%. In practice the Application Virtualization overhead will be highly dependent on how often virtualized applications are started, and how much file IO and registry access they generate: specifically the creation of the virtualization 'bubble'/environment for the application can have a significant overhead.