We recently ran a proof-of-concept project using Citrix XenDesktop to host 3 virtual machines. Whilst we specced out the virtual machines to match current desktops in terms of memory and CPU, we found that there were some serious issues with performance when using eningeering tools such as IBM Statemate design tool and Greenhills AdaMulti compilers. We found that the virtual environment didn't handle page faults and context switching at all well, meaning that some of our software builds were taking around 50% longer to complete on a virtual environment compared to our desktops.
Dan. Typhoon Integration & Deployment Team, BAE SYSTEMS.